Xenosaga Episode I: Der Wille Zur Macht Missable Achievements Guide - RetroAchievements/guides GitHub Wiki

Set developed by FBernkastelKues, guide written by benit149

Hello, and welcome to my missable achievements guide for Xenosaga Episode I: Der Wille zur Macht (“The Will to Power”). It is the first game in a trilogy that encompasses a single storyline, with players able to unlock a bonus in the subsequent title after clearing the prior entry’s story. The plot is related to Xenogears, but is essentially its own story.

Unlike with other JRPGs where I go in-depth into the mechanics, I won’t be doing so here since I believe the game’s tutorial handles explaining the basics well enough. It might be slow and tedious, but I strongly suggest you do so since it’s not quite the same as a standard JRPG battle system. There is an advanced technique I will be covering once a particular boss challenge comes up, so get used to how basic combat works first before arriving there.

One thing I would like to point out is that the six main characters are divided into two categories – humans, and machines. Shion, chaos and Jr. are considered humans, while KOS-MOS, Ziggy and MOMO are machines. These classifications are vital to know for particular challenges, as well as understanding that only the humans can use the AGWS (Anti-Gnosis Weapon System), which is just another term for a mech.

Another thing to mention is that, apart from some specific instances, there’s no need to fret if you miss any treasures during your first trek through an area, even if you think you might have. There is an in-game method of using a virtual simulation to return to lost areas to retrieve items you couldn’t possibly get the first time around. This involves a convoluted system of locked red doors called Segment Addresses, of which there are 18 of them. First you need to register the Segment Address by examining the door. Then proceed with the story until you find its related key later on, called a Decoder. Once you’re able to, return to the Segment Address (the door) and use the Decoder (the key) to unlock it, granting you access to the treasure chest inside.

For instance, let’s take the KOS-MOS Simulator right at the beginning of the game. As you explore, you will come across one of these red doors. This is Segment Address No. 10, which you obviously cannot open right now. Once you get Decoder 10 on the Elsa a little later on, you can jump back into the KOS-MOS Simulator and return to the door to unlock it. This is basically the game’s way of forcing you to backtrack to previous areas for missed treasure.

With that covered, let’s get into the missables themselves. You’re going to be bombarded with a lot of missables and game mechanics you need to remember at the start, so pay attention. Be warned that there are heavy spoilers involved. If you wish to enjoy the plot for the first time, please stop reading here.

MISSABLE ACHIEVEMENTS

What Lurks Behind the Door (5)

Fill out the Segment Address Database

As I mentioned in my opening spiel, there are red doors called Segment Addresses and specific keys called Decoders you need to find to open the doors later. It’s impossible to open all of the doors in your first run of an area, but the game provides a virtual simulation you can use to backtrack. This is missable due to a bug in the game involving Decoder 16, which I will explain in further detail when it becomes relevant. If you don’t get Decoder 16 during the proper time, this also makes OSHA Violation impossible to complete since Segment Address No. 16 is on the Woglinde.

A Glitch in the System (5)

Defeat Drone GX with KOS-MOS using no more than 2 AP per turn (Level Limit: 4)

Not hard at all. KOS-MOS must only use one attack and guard anytime her turn comes up. Meanwhile, Shion needs to jump into her AGWS, and she can pummel the boss however she wants. Make sure to read the achievement's comment section since there seems to be an issue where you are forced to do one attack and then guard, rather than just guard to skip KOS-MOS' turn.

OSHA Violation (5)

Collect every treasure in the Woglinde

The Woglinde is the first spaceship that you run around in as Shion. While 95% of the items cannot be lost (and none of them really should be), Segment Address No. 16 is potentially missable if you don’t follow the correct steps while invading the U-TIC Battleship as Jr. later in the story. I already mentioned why in What Lurks Behind the Door. You won’t be acquiring this achievement until the end of the game anyway due to the Segment Addresses.

Hacker Wars (5)

Capture the Vector hacker and obtain your reward

This is a chain of emails that Shion can receive that involves capturing a hacker. The first email occurs in the Woglinde when you speak to the Realians on the beds, go through the cutscenes, then turn back south into the examination room. As long as you’re following a comprehensive guide, you shouldn’t have any trouble getting this. Just make the correct answers as the emails come up. The payoff will not occur until way later when you clear Song of Nephilim, with the final reward being 200,000 G.

Goddess of Tag (5)

Avoid being tagged for 60 seconds

While wandering around the Woglinde as Shion, you’ll come across two guys in dark armor who goad her into playing tag with them. You need to hurry over to the upper left hallway and reach the maintenance man standing there. Run to the other side of him, and the two soldiers will be stuck on the other side unable to reach Shion. Stand there for a minute until this pops, let them catch you, then redo the minigame for the item.

Genesis of Destruction (10)

Defeat 1 of every Gnosis

This is the only achievement in the set not marked as missable, but actually should be. Once the Woglinde is attacked by the freaky space monsters known as Gnosis, this is where this achievement’s requirements begin. Be sure to fight at least one type of each Gnosis you come across throughout the game, of which there are 26 in total. In particular is the Wyrm, found during the Kukai Foundation invasion. It is a problematic Gnosis because there’s only one, and it is able to run away, meaning you only have a single chance at it. I had personally messed up on this during my first run because I didn’t fight the Sky Fish only seen flanking the Minotaur boss. Likewise, the small enemies flanking the Gargoyle need to be attacked, and you need to kill one of everything during the Kukai Foundation invasion.

Another achievement tied to this is Crystalbound Chant, but that won’t be until MOMO defeats an optional boss as early as the Kukai Foundation invasion, so it’s not relevant for now. Just get familiar with the Gnosis and where they’re located. I’ve made a quick checklist if you want to be sure, listing the Gnosis, where it’s located, and if it’s missable.

  1. Drone G1 – KOS-MOS Simulator
  2. Drone G2 – KOS-MOS Simulator
  3. Drone G3 – KOS-MOS Simulator
  4. Manticore – Woglinde
  5. Goblin – Woglinde
  6. Sky Fish – Woglinde (accompanies Minotaur, is missable)
  7. Cerberus – Cathedral Ship
  8. Fairy – Cathedral Ship
  9. Basilisk – Cathedral Ship
  10. Ogre – Cathedral Ship
  11. Hydra – Cathedral Ship
  12. Unicorn – Cathedral Ship
  13. Lizardman – Cathedral Ship
  14. Oudogogue – Cathedral Ship (accompanies Cyclops, is missable)
  15. Bugbear – Encephalon
  16. Kobold – Encephalon
  17. Larva Doll – Encephalon
  18. Troll – Encephalon
  19. Gel Fish – Kukai invasion (missable)
  20. Wyrm – Kukai invasion (HIGHLY missable! There is only ever one in any given Xenosaga I run, and it is able to escape from battle. You MUST kill it at this time!)
  21. Larva Face – Kukai invasion (missable)
  22. Delphyne – Proto Merkabah
  23. Demon – Proto Merkabah
  24. Armaros – Proto Merkabah
  25. Barqijal – Proto Merkabah
  26. Azazel – Proto Merkabah

Fusion Gone Wrong (5)

Defeat Cyclops using nothing but Ether attacks (Level Limit: 5)

Not a hard one either, but you do need to know that Shion and KOS-MOS’ Triangle combos are considered Ether attacks, whereas both of Virgil’s attack types are not. Don’t attack the boss with Virgil, having him guard or heal the others when his turn comes up.

Heavy Artillery (5)

Defeat Minotaur using nothing but gun attacks (Level Limit: 9)

Can’t say I remember anything difficult about this boss. Just avoid using Square button combos and focus on Minotaur to get rid of it quickly. Be sure to kill at least one of the Sky Fish for Genesis of Destruction as well!

Under Cover of Night (10)

Rescue MOMO and make it to Margulis without being noticed by a patrolling guard and only fighting 3 battles in one session

Ah yes, one of the banes of my existence as a gamer – shoehorning stealth mechanics into a JRPG. The stealth portion truly begins once Ziggy loses his invisibility and has to start proceeding right through the next two rooms with patrolling guards. Not only is this section long and tedious, it is further complicated by not being allowed to fight outside the three mandatory battles you are thrust into (two soldiers, a robot, and three mechs respectively). Alerting any of the guards is an automatic fail, as well as getting into an encounter with one of the spinning drones that chase Ziggy and MOMO through the corridor with brown sludge. The worst part is that I accidentally got into a fight with one of those things, then fought the three AGWS without the achievement notification disappearing to tell me I had failed. Only after I had finished that slog of a fight did the icon disappear, which meant I had wasted my time with the battle. Quite frustrating, indeed.

Instead of trying to explain how to do this, I made a video guide showing the route. Be sure to read my notes either in the achievement’s comments section or the video’s description for additional details. I do want to point out that I didn’t bother with picking up any treasures during my attempt, and it turned out I was right to do so. It isn’t possible to acquire everything without being spotted because you need to defeat the green AGWS after rescuing MOMO to acquire the Decoder 4, which opens Segment Address No. 4 to the chest containing the Thief Ring. Thus, this and A Sacred Place are mutually exclusive to each other and must be done in separate attempts. If you want to save this for later, make a backup save.

Fight Into Enemy Territory (5)

Defeat Margulis on Pleroma

Once Ziggy and MOMO get out of the stealth section, a boss battle against Margulis will occur. There is the option to lose the battle, which you obviously don’t want to do. Regardless if you’ve done the stealth section or not, you need to do a fresh run to nab all of the treasures on Pleroma. Some of them will be stat-boosting items that can be used during battle. One of these is the Stim, which boosts attack power. Use it on Ziggy and have him use physical combos on Margulis. He is highly resistant to Ether combos, so don’t use the Triangle button for attacks. Margulis does have the ability to absorb either fire- or lightning-elemental attacks, which are Ziggy’s elements as well. If you see one of these absorbing abilities come up, use the other combo to do damage instead. MOMO should be positioned behind Ziggy and healing him.

Shipmeister’s Shanty (5)

Collect every treasure in the Elsa

You need to collect everything you can before Ziggy and MOMO’s ship is rescued by the Elsa. This story trigger causes the contents of the breakable objects to change. Due to how complicated finding the Elsa’s items is, I’ve made a quick checklist for it. You want the count to be at 22 of 48 before activating the cutscenes with Ziggy and MOMO (you can’t get the Segment Address items yet, so you’ll be two short from what this list says). As long as you do everything correctly from there, you should ultimately be at 46 of 48 items at this point in the story.

  1. B1 – blow up object just north of elevator – Ether Pack
  2. B1 – through door with red light, blow up box – Med Kit
  3. B1 – same as #2, but one of small blue boxes – 2 Ether Upgrade S
  4. B1 – same as #3 – Med Kit
  5. B1 – blow up two objects concealing a passageway to some boxes – Ether Upgrade A
  6. B1 – same as #5 – 50 G
  7. B1 – from #5, go east and down some steps, boxes at bottom – 150 G
  8. B1 – same as #7 – 200 G
  9. B1 – behind Segment Address No. 8 – Robot Part Left Leg
  10. B1 – use Disarm Key on console to complete cross-shaped bridge, take east path – 200 G
  11. B1 – same as #10, but go down stairs at west path – Spirit Pendant
  12. B1 – same as #11 – Decoder 10
  13. B1 – same as #11 – 50 G
  14. B1 – same as #11 – Bio Sphere
  15. B1 - back to cross-shaped bridge, take north path, then head left – 5 Ether Upgrade A
  16. B1 – same as #15 – Med Kit
  17. B1 – same as #15 – Bio Sphere
  18. Catapult Room – behind Segment Address No. 14 – Speed Shoes
  19. Catapult Room – Fiber Suit
  20. Catapult Room – 150 G
  21. Catapult Room – 100 G
  22. Catapult Room – Ether Upgrade S
  23. Hangar A – from save point room with chaos wandering around, go through south door, down elevator, and hug left side of room to find some boxes – 5 Ether Upgrade A
  24. Hangar B – from #23, go south into next room, then go all the way south to find a chest – Coat-Beam
  • The Elsa invasion is when the destructible objects’ items will be restocked
  1. B1 – same as #1 – Ether Pack
  2. B1 – same as #2 – Ether Pack
  3. B1 – same as #2 – Escape Pack
  4. B1 – same as #2 – Bio Sphere
  5. Catapult Room – 5 Skill Upgrade A
  6. Catapult Room – Ether Upgrade A
  7. Catapult Room – Antidote
  8. Catapult Room – Ether Upgrade S
  9. Catapult Room – Ether Upgrade S
  10. Catapult Room – Antidote
  11. B1 – same as #15 – Frame Repair A
  12. B1 – same as #15 – Skill Upgrade S
  13. B1 – same as #15 – Antidote
  14. B1 – same as #10 – Bio Sphere
  15. B1 – same as #11 – Antidote
  16. B1 – same as #11 – Ether Pack
  17. B1 – same as #11 – Frame Repair A
  18. B1 – same as #11 – Med Kit S
  19. B1 – same as #7 – Escape Pack
  20. B1 – same as #7 – 2 Skill Upgrade A
  21. B1 – box at top of stairs from #44 – Med Kit S
  22. B1 – blow up objects concealing the hallway, one of the panels has this – Escape Pack
  23. B1 – same as #5 – Ether Upgrade S
  24. B1 – same as #5 – Escape Pack

Cybernetic Uprising (5)

Defeat Domo Carrier using a team of machines (Level Limit: 15)

If you read my intro to this guide, you’ll know that there is an advanced combat technique coming up, and that it involves using the party members designated as machines. Now is that time. During regular combat, you may have noticed a rectangular icon on the lower left of the blue turn order window that has icons which cycle every turn. That is the Event Slot, of which there are four icons that will always appear in this order upon initiating a battle; a yellow ring, a burst of fire, a gold coin, and a grey square. These slots are Boost Up, Critical Up, Points Up, and Nothing respectively. Boost Up increases the amount of boost gauge a character earns during regular attacks, shown as a red bar beneath their health. Critical Up increases their attack’s damage output. Points Up awards more Tech Points, Skill Points and Ether Points upon defeating an enemy. The grey slot gives no beneficial effects whatsoever, but is relevant for the next part.

Going forward, the bosses will now start to play games with the Event Slots. Here, Domo Carrier will designate one of the slots to activate its Tremor attack, so keep a mental note of which one it is. For me, it was Points Up, so I’ll use that as my example. Should its turn come up when the Points Up slot is active, it will perform Tremor, which damages everyone and is very hard to recover from. I don’t believe the game gives this concept a term, so I’ll call it the Designated Slot.

Luckily, you can game the system as well to prevent this from happening. Your characters’ boost gauges come into play here with the Boost System for this purpose. When someone’s turn comes up and you see that Domo Carrier’s turn will definitely appear on its Designated Slot next, hold the R1 button and the characters’ icons will come up if they have at least one boost gauge charge. From their positions on the field going left to right, they are assigned to Square, Triangle and Circle. Choose a character with sufficient boost gauge, and their turn will immediately come up next, regardless if the boss is supposed to go next.

So in my example, I have MOMO’s turn on Critical Up, and Domo Carrier is about to act on Points Up next, which is bad news for me because that’s the Designated Slot. KOS-MOS has one boost, so I hold R1 and press Triangle to choose her as my boosted character. Now when MOMO’s turn ends, KOS-MOS will act on the Points Up slot instead of Domo Carrier, forcing it to act on the Nothing slot instead. Crisis averted for now. As long as I manage to force Domo Carrier to miss the Points Up slot, I will be safe from Tremor.

Aside from Tremor, another annoying thing the boss does is heal itself for 600 HP on the Nothing slot (at least it did for me, it might be different for you). Thus, I ideally want it to act only on Boost Up or Critical Up to perform a much less dangerous regular attack. There won’t always be enough boost gauge for this though, so you’ll have to take the heals as they come up over suffering through too many Tremors. You also can’t use any party members besides Ziggy, MOMO and KOS-MOS for this fight since they’re considered machines, so you have no access to Shion or chaos’ AGWS. This will take some patience and learning, but it will serve as a useful tutorial for handling future challenges.

Residential Quarters (3)

Give a complete tour of the Elsa

This happens immediately after defeating Domo Carrier. Shion gives Ziggy and MOMO a tour of the Elsa, and there are nine locations tied to this.

  1. Cabin 2, which is Shion’s room where the tour begins, and is automatic. Be sure to say no when the prompt comes up to continue the tour. When you want to return to the story, come back here and have Shion rest
  2. Cabin 1, directly north of Cabin 2
  3. Enter the bridge at the far north of the first floor
  4. Take the southeast path to the kitchen. Alternately, enter the rightmost door in the restaurant
  5. Small save point room near Hangar 1
  6. Upper right area of hangar
  7. Enter room in upper left area of Hangar 1
  8. Go all the way south in Hangar 1 to reach Hangar 2, where Domo Carrier was fought
  9. Catapult room, where Ziggy and MOMO’s ship was

One thing I recommend doing at this time is returning to the KOS-MOS Simulator and unlocking Segment Address No. 10 with Decoder 10. As long as you looted everything else here, you should get Lost in the Simulation.

You will transition to the U-TIC Battleship invasion by Jr. and his cohorts. He starts at level 12, and the boss challenge’s minimum level requirement is indeed 12. Make sure he doesn’t gain any levels while exploring the battleship.

One More Robot (1)

View the schematics for an upcoming character

While looting the U-TIC Battleship, you’ll come upon a room hiding the U-TIC Card in a chest. That same room also has some schematics for something called T-ELOS on a blue monitor for Jr. to view. At the time this game was released, it was an easter egg for an upcoming character introduced in Xenosaga Episode III.

The Assault of the Combatant Ship (5)

Collect every treasure in the U-TIC Battleship

Segment Address No. 11 is found here, which you should have acquired Decoder 11 during Ziggy’s events in Pleroma. As long as you’re following a guide, you should find all 20 items here no problem. The reason why this is missable is that after getting the U-TIC Card, you NEED to unlock a door with it that leads to the chest containing the Decoder 16! You don’t have to open the chest if you don’t want to (which would be silly IMHO), but it’s important that you unlock the door first! While the U-TIC Battleship can be returned to later on, using the card any time after the intended story point (as in right now) will cause the game to freeze due to a notorious glitch. If you fail to unlock this door prior to fighting Ambix, this likewise makes getting all of the Woglinde’s treasure impossible because Segment Address No. 16 is located there, as I mentioned earlier. Yes, I know I’m sounding like a broken record at this point, but it is extremely important to highlight this so you don’t accidentally screw yourself.

My Time to Shine (5)

Defeat Ambix with just Mary and the soldier making a move (Level Limit: 12)

During the U-TIC Battleship invasion, Jr. is accompanied by two characters who are always in AGWS units – Mary, and a generic soldier. These are the only two characters you want to be performing any moves during the battle, while Jr. is forced to do nothing but guard. Since Jr. can’t heal himself, nor can either of the others due to them being in mechs, be sure to have Jr.’s health topped to max before entering the fight. In short, you’re supposed to rush down Ambix with Mary and Soldier. I’m not sure if Jr. is allowed to die, but to be safe, I went all out to take it down ASAP. As long as you do the same, you shouldn’t have any issues with the characters at their default levels.

Voices Broken (5)

Help Luty open up to others

You won’t be getting this achievement until later, but you do need to initiate the trigger for it now. At the Dock Colony, go to the clinic and speak to everyone inside to learn about the mute girl Luty. Proceed until you reach the Cathedral Ship, where you will find Flower Seeds. Return to the Dock Colony and give the seeds to Luty in the clinic’s reception room. You need to speak to her after every time you clear a major dungeon, so you only have a limited number of times to visit her before running out of areas. From this point in the story, there are the Encephalon, the Kukai Foundation invasion, and the Song of Nephilim, so be sure to speak to Luty whenever you clear one of these areas. I don't believe Proto Merkabah, the final dungeon, is part of this since you technically can't 'clear' it like the others. If I'm wrong, please let me know.

Enemy Ship Invasion (10)

Defeat Gargoyle without attacking on high critical event slot (Level Limit: 19)

Just like with Domo Carrier, you need to pay attention to your Event Slots. This time, you need to avoid having your characters use the Critical Up slot (the fire-looking icon) for attacking. They are allowed to be on that slot, but you must do something other than attack. If you're going for all of the Gnosis kills for Genesis of Destruction, at least one of the lesser enemies needs to be killed here as well for that. This will be a long and drawn-out fight, especially since every enemy can do an AoE attack that hurts everyone, and Gargoyle has 3600 HP.

Before starting, be sure that Shion has learned Medica All and spread it to at least two of your active party members. I stuck with the same party as Domo Carrier, but you can use whoever you want. For me, MOMO and KOS-MOS received Medica All, with MOMO as the primary user and KOS-MOS for emergencies. Ziggy’s only jobs were to guard, attack, and throw Ethers on MOMO as needed. Pay sharp attention to the Event Slot as it cycles, and don’t attack on Critical Up. Luckily, none of the enemies fool around with Designated Slots, so there aren’t any shenanigans to worry about there. Kill one of the flunkies, and its death will power up the boss a bit. I left the other one alone to not strengthen the boss too much, but feel free to kill it too if you want. Gargoyle can also cast Lost (a.k.a. Silence) on one character, which is why you want at least two characters able to cast Medica All. Use a Neuro Stim or Cure All to cleanse it, especially on your primary healer ASAP.

It takes a little while, and it may be too easy to lose focus and accidentally attack on Critical Up. If you need to take a short break to refocus, do so. Some of these boss challenges can be quite tedious to do in one full sitting. I also recommend stealing from Gargoyle since it has the rare Commander’s Crest accessory which boosts AP by 1 every turn, freeing up anyone who has the skill from having to guard to build up the AP.

Two Tickets to Paradise (5)

Collect every treasure in the Kukai Foundation

The Kukai Foundation area is broken up into three distinct segments – pre-invasion, invasion, and post-invasion.

Pre-Invasion: while there are 9 items available, you can’t get one of them because it’s an inaccessible chest behind a counter at the hotel. Thus, you’ll be leaving for Encephalon with 8 items acquired

Invasion: the chest can now be acquired to bump you up to 9 from Pre-Invasion, plus 14 more items during Invasion. Your counter should be at 23 of 26 once you’ve collected everything

Post-Invasion: 3 more items before you go to rescue MOMO from the Song of Nephilim. Don’t speak to Captain Matthews in the Elsa to depart for Song of Nephilim until you do this! All 3 should be found on the map of Area 26/27. Watch out with this segment because the guide I was using neglected to mention these treasures, so I assume they were not very well known at the time. One item is in the Ironman bar, another is in one of the large dumpster bins that you needed to access by dropping from the hotel’s roof (you can open the gate now), and the last one is in a desk at the dry cleaner’s shop.

Face My Fears (10)

Defeat Tiamat with Shion by herself and then with Jr. by himself (Level Limit: 27)

This boss battle is considered one of the hardest in the game as it is, so adding restrictions to it makes things much worse. Since there are a lot of things you need to do to prepare for this, I’ll write it as a simplified to-do list:

  • the third character can be whoever you want, but Ziggy is the best choice since he can tank the boss’ AoE attack the best, so I’ll be using him as my example
  • boost Shion and Jr.’s stats with Tech Points, focusing on VIT and EDEF. You may do other stats if you wish, as long as you don’t grind past level 27
  • boost Shion’s Skill Level to 3 so she can extract Confusion Guard from the Blade Soul accessory. It’d be a good idea to boost Ziggy’s Skill Level for the same reason. I had a close call where Ziggy got confused, but Shion’s turn came up before his, allowing me to cleanse it. Otherwise, Ziggy’s actions would have invalidated the achievement. Another idea is to throw a Hemlock at Ziggy to let him die during the fight, but with proper grinding, this won’t be needed
  • equip the Blade Soul and White Ring on Jr.
  • equip the Angel Soul and Double Buster on Shion
  • boost Shion’s Spell Ray tech to level 5 and set it as her HI combo. After guarding to get 6 AP, this lets her perform a Firecracker -> Spell Ray -> Spell Ray combo to do about 600 damage per Spell Ray, so approximately 1200 damage per combo. Considering that Tiamat has 6400 HP, the damage is very much needed
  • set one of Jr.’s combos to be Storm Waltz and boost it as well
  • for Ether spells, transfer Medica Rest from Shion to Jr., with Medica All as another option

From there, only have Shion take turns while the other two guard. Keep up the pressure until the message, “Consciousness against Shion destroyed.” Tiamat will then heal itself for 1500 HP, which is your time to switch over to Jr. for offense. Now guard with Shion and Ziggy while Jr. takes actions instead. Since it’s just 1500 HP you need to whittle down with him, plus he doesn’t have the Double Buster equipped to do the same levels of damage as Shion, it shouldn’t take too long to defeat Tiamat with some Storm Waltzes. Remembering that you’ve done the transition might be the hardest part since you’ve gotten into the rhythm with Shion, only to be interrupted for Jr.’s phase.

Be warned that for whichever two characters have to be on standby, guarding is the only thing they’re allowed to do! Never throw items, cast spells, attack, use AGWS, or anything else!

After defeating Tiamat, keep Shion’s setup as it is and bring her into the next story boss challenge against Gigas. Make sure her AGWS also has an AoE attack.

Battling Despair at Dawn (5)

Collect every treasure in KOS-MOS' Subconscious Domain

This is not missable, but a couple of treasures are vague enough to warrant being covered here. I had not found 3 items in my initial story run of Encephalon, of which 2 are not available until you revisit it in the virtual simulator. The regular item was hidden in a tree trunk near the church where Tiamat is fought. The first item that requires the revisit is in the same room of the church where you fight Tiamat, which is now a bedroom with a chest containing a Star Hat. For the other item, backtrack to the very beginning of Shion's segment in Miltia Park and look for the small playground with the dome at the very south. Have your on-screen character be either MOMO or Jr., then inspect the dome to find the PM Card A.

During the Kukai Foundation invasion, you will have to fight Mintia if you want to get Crystalbound Chant, so her challenge will be placed here instead of later.

Serena Ira (10)

Defeat Mintia with two men in the party and without MOMO making a move (Level Limit: 40)

Mintia has 7777 HP, but the trouble is that she hates it when men attack her. Be sure your males have protection from Attack Disable. Mintia also forbids you from using AGWS mechs in this fight, but you won’t need them. My party was MOMO, Jr. and chaos, with MOMO standing behind Jr. You have the option to save this for later in the game if you want to build up levels, but you’d miss out on having MOMO use Dark Scepter on Gigas to have a Diamond in your inventory for Crystalbound Chant.

While the fight is straightforward, there is an attack where Mintia will summon her servant. Pay attention to the color of the magic circle beneath her. If it’s blue, the monster will do an absorption attack that leaves the targeted ally at 1 HP while healing Mintia for the amount it absorbed if it is not guarded against. If it is guarded, it will only take half of the character’s health. If the magic circle is pink, it will do a much weaker AoE gravity-type attack that can’t kill anyone, so don’t worry if this goes off immediately after the blue magic circle attack. For this reason, it’s not a good idea to have your primary attacker at full health all the time, but you also want them to have enough HP to weather her regular attacks. Med Kit DX comes in handy at this time, along with weaker healing spells like Medica and Life Shot, aside from Medica All.

Since Mintia is highly resistant to Ether attacks, it wouldn’t be smart to bring Ziggy to this battle since his Triangle combos are Ether attacks, and Mintia is an airborne enemy that can’t be targeted with Square combos. The same goes for chaos, so I had him on support duty and never attacked with him. This leaves Jr. to be on offense with Storm Waltz, just like with Great Joe. Keep track of Mintia’s HP since it’ll be constantly going up and down, and blow her away with a single Storm Waltz rather than a double as the killing blow if you’re able to. Don’t forget that she can guard though, so perhaps do a double to be on the safe side if you’re not confident.

Crystalbound Chant (10)

Hold at least one of every gemstone

After defeating Mintia, she will teach MOMO the ability Dark Scepter, which allows her to turn enemies into items. You have to transform Gigas during the Kukai invasion since that is the only time it is available, and it is not in the virtual simulator! There are five gemstones to acquire, and you must have one of each in your inventory:

  • Garnet: Drone G1, Drone G3, Goblin, Kobold, and Manticore
  • Sapphire: Fairy and Hydra
  • Ruby: Basilisk, Bugbear, Cerberus, Golem and Tiamat
  • Emerald: Unicorn and Wyrm
  • Diamond: Gigas

How to Make Clones (10)

Defeat both Gigases at the same time (Level Limit: 31)

When you encounter the Gigas during the Kukai invasion, it will split into two. Keep a notepad and a calculator handy because you’ll want to keep track of their HP values as you damage them. To make things easier, I’ll label the left one as Gigas A and the right one with the staff as Gigas B. Both of them have 2800 HP, but Gigas A is weak to Ether attacks while Gigas B is the same with physical attacks. I had my party be Shion, MOMO and Ziggy, with Shion as the MVP for two reasons – she still had her setup from the Tiamat challenge, and her AGWS will be responsible for killing both Gigases simultaneously.

While Gigas A doesn’t have any particularly dangerous attacks, Gigas B will be able to instant KO a character two or three times when its health gets low. It won’t constantly spam this move, so once those few times are exhausted, you’re pretty much safe. Chip away at their health until both of them are just under 100 HP each. When I was approaching that number, I had Ziggy use Ether attacks on Gigas A and Shion use physical attacks on Gigas B to carefully bring it down further. Once ready, Shion should now get into her mech and blast them to oblivion with the AoE attack I told you to put on earlier.

After clearing this challenge, reset so you can have MOMO morph one of the Gigases into a Diamond.

Once you’re completely done with Kukai, and if you’ve done everything else involving Luty, go back to the Dock Colony and speak to her. This should be the first opportunity for you to receive Voices Broken at last, along with a Tech Upgrade Z from her. If not, there’s still Song of Nephilim to clear. Just remember to visit Luty and you should get this.

Invisible Chains (5)

Defeat Rianon Se without boosting (Level Limit: 34)

This is essentially the opposite of Cybernetic Uprising where you wanted to boost at the proper time to avoid Domo Carrier’s dangerous attack. Here, just avoid pressing R1 to boost a character’s turn. This fight will take a while since Rianon Se can boost itself many times, and can absorb your characters’ health to heal itself. It’s even worse if you’re in an AGWS because the absorption damage is greatly increased. Rianon Se is more susceptible to physical attacks, and likewise highly resistant to Ether attacks. If needed, you can throw the Stim DX you got from Segment Address No. 16 in the Woglinde onto someone for a good damage buff.

Humans vs. Gears (10)

Defeat ES Simeon without using AGWS (Level Limit: 37)

Have a character with good EATK equip the Double Buster, as well as have Medica All on everyone. Medica Rest would also be a good idea. The only restriction is to never get into the human characters’ mechs, so just attacking as normal will be fine. Simeon has a specific pattern that needs to be exploited - the camera will first zoom in on a character while Albedo does some crazy talk, meaning you want to guard with that character. On Simeon’s next turn, it will do Aird E, a deadly single attack on the targeted character, unless you were smart enough to guard. After Aird E goes off, Simeon’s EDEF will temporarily plummet, allowing your EATK character(s) to go all-out with their Ether combos. Slip in as many boosts as you can during this time for maximum damage output. On Simeon’s turn after Aird E, its EDEF will return to normal, so you need to repeat this process a few times.

Simeon will start becoming harder to deal with because it too will boost a lot, even going so far as to overtake your characters’ boosts. This makes it trickier to time when to do big damage. It becomes a waiting game of healing everyone’s HP and EP, guarding at appropriate times, and attacking when the opportunity presents itself. You’ll have to play defensively, but Simeon will go down eventually since it has no healing abilities.

Human Strengths and Weaknesses (25)

Defeat Ein Rugel and Doppelwogel without recovering status effects (Level Limit: 39)

Good lord, this achievement is horrible. It is definitely the hardest of them all, so get ready to do some serious prep work.

This fight happens immediately after Simeon, but you do have the chance to regroup and save. This challenge forbids you from cleansing status ailments, which both Ein Rugel and Doppelwogel love to inflict on your allies. This also means that ailments which wear off on their own will also invalidate the achievement. I did notice that Slow wearing off didn’t affect the achievement, but others like Confusion and Attack Disable did. Even reviving someone from KO wasn’t allowed. The logic behind which statuses are affected is poorly understood among the community, and I also had a hard time figuring out what was going on even with carefully analyzing my multiple attempts. The developer hasn’t provided any notes regarding this, so all I can do is give you my own findings.

So what are you supposed to do? Two things - prevent yourself from getting most of those ailments in the first place, and dump Tech Points into combo attacks so you can rush down both bosses. You will need to build up your characters’ Skill Points and invest in extracting Attack Disable from Soldier’s Honor, Confusion Guard from Blade Soul, Stop Guard from Field Ring, and Sleep Guard from Nightwalker. Stop and Sleep will only be useful to anyone hopping into a mech, so don’t give those to your machine allies. Everyone should have Attack Disable and Confusion Guard, while I found Sleep Guard to be more useful than Stop Guard. Another idea is to buy Cockpit Guards for your AGWS to prevent Sleep and Confusion for the pilots, freeing up those skill slots for other status protection abilities. You have a lot of leeway as to how you want to manage these skills.

KOS-MOS’ Arm Cannon can wipe the floor with Ein Rugel, so boost that first. It won’t be effective on Doppelwogel because it is highly resistant to Ether attacks. Everyone’s Triangle combos are Ether combos except for Jr.’s, so get him in the party and boost his combos too. I also had KOS-MOS equipped with F-RSHOT, which did good damage against Doppelwogel as well. I doubt I would have been able to do effective damage while using items to heal if it wasn’t for that. My third character was Shion, but she was more for support. Some players have said that spells like Medica All and Medica Rest randomly invalidate the achievement for whatever reason. To avoid this, I used Med Kit DX for healing instead, and it was safe to do so. Another idea is to spread spells that boost a character’s attack and speed. I had Psycho Arm on Jr. and KOS-MOS, while Shion had Quick unlocked.

Don’t be surprised if this takes you a few attempts. It was incredibly annoying for me to figure it out, and I still don’t fully understand what was happening. What’s even more annoying is that both bosses tend to evade attacks at a surprisingly high rate. All of that effort put into building up AP for that powerful attack on a Critical Up turn? Wasted with a dodge. This achievement nearly ruined the set for me, but with enough patience and grinding, I was able to do it.

Aside from fighting Great Joe now, you will also be cashing in on some achievements you started on earlier.

Gunslinger’s Glory (10)

Defeat Great Joe with Jr. being the only one to make a move (Level Limit: 40)

My party was Jr., chaos and Shion, with her positioned behind Jr. so he could take advantage of his Ether spell Dandyism, which revives him if a female ally is behind him. I also transferred Shion’s Safety Level to Jr. to add an extra layer of revival in case Dandyism wasn’t enough, along with transferring Medica All and Medica Rest for healing. I also had Jr. unlock Speed Machine, and kept Psycho Pocket for stealing.

For skills, you definitely want W Special, Damage-10 and Sword-20. W Special is from Double Buster, Damage-10 from Cross, and Sword-20 from Coat-Sword. The first skill was to allow Jr. to perform Storm Waltz twice when he reached 6 AP, and the other two skills were to help reduce damage. I had Jr. equipped with a Commander’s Crest (stolen from Gargoyle) and Silver Crown. I also boosted Storm Waltz to level 10, which was letting me do around 600 damage normally or about 900 if critical. Great Joe has 9999 HP, so this is going to take a little time and luck depending on what he does.

Once Jr. has applied all of his buffs and stolen from Great Joe, it’s just a matter of using Storm Waltz on him repeatedly and healing as needed until he goes down. Shion’s purpose was just for Dandyism, while chaos was there to tank some hits due to his decent HP pool. Ziggy or KOS-MOS can handle this as well if you prefer either of them. Otherwise, just guard with your allies and have Jr. doing all of the work. Eventually, Great Joe will perform a devastating attack that can instantly kill Jr., so this is why you wanted Dandyism and Safety Level active. Be absolutely sure not to use a Cure-All during this fight because it will remove these beneficial statuses as well.

Once you get him down to enough health, Great Joe will talk to Jr. before performing a move that has a 50% chance of reversing his vulnerability to regular damage. This would make him just like the Larva Dolls and Larva Faces you’d have seen by this point, where you need to use healing to damage them. Just perform one basic attack with Jr. to confirm if the vulnerability has been switched, and respond accordingly.

After finishing Great Joe off, I went and fought Mintia for that challenge, but failed to realize that Gigas is a one-time enemy during the Kukai invasion. Bugger… Regardless if you made the same mistake or not, upgrade your AGWS as much as they can go for the next challenge in Proto Merkabah. There is a long jump leading into the encounter with Proto Dora, but there is a door that can be unlocked afterward which will let you return to the Elsa. Since Segment Address No. 6 is also found in the area after the jump, get all 17 of the other doors open before making the plunge so you can take care of What Lurks Behind the Door as well. The game's point of no return is when you enter the room that triggers the boss battles against Albedo and Sophie Peithos.

Robot Army (10)

Defeat Proto Dora using nothing but AGWS (Level Limit: 43)

Have your mechs equip the same weapons in their hands so they can perform W-Act. I stuck with axes you can buy so I didn’t need to worry about my supply of bullets. Proto Dora has 12,000 HP and is accompanied by two lesser Schutz mechs, but you can just ignore them and focus on the primary enemy. The achievement icon will not show up until everyone boards their AGWS, so having a party of either Shion, MOMO, Jr. and/or chaos is mandatory here. Definitely have Guard Recovery equipped on your mechs so that they can regain 10% of their HP every time they guard.

There are two huge problems with this battle. One is that your AGWS won’t be doing a lot of damage, especially if they have bad weapons equipped. The other is that Proto Dora will do Relief Goods once in a while, healing itself for 2380 HP. Considering that your mechs are doing about 500 damage at best with W-Act and axes equipped, this is going to take an absurdly long time to finish. If you’re struggling with this battle, return to the Dock Colony via the Elsa and boost your mechs at the shop.

One thing I did was buy the AG-05 mech and replaced Shion’s default VX-10000 with it. It’s a hefty 300,000 G, but it comes with 6000 FHP which is a huge improvement from the around 2000 FHP you’d have even with upgrading. Coupled with Guard Recovery, it’ll become much easier to keep this mech alive during such a long fight. The other two AGWS were doing about 500 damage, while this one was pumping out just over 1000, allowing you to keep up with the healing from Relief Goods.

Iron Will March (10)

Defeat Albedo with MOMO being the only one to make a move (Level Limit: 46)

Now that your level limit is as high as it can go for these challenges, it’d be a good idea to reset after defeating Proto Dora and boost both MOMO and chaos’ stats and abilities. Albedo is more susceptible to physical attacks, so focus on those Techs for MOMO. She will also need all the speed boosting she can get such as White Ring, Speed Shoes, and Ether spells like Quick or Speed Machine. You will want chaos in the party for the next challenge, while the third character doesn’t matter. Those two characters can only guard during both this and the next fight.

I also want to point out that while doing your level grinding, do not go past level 44 or 45. This is because several enemies will attack the party during the final elevator descent and you’re unable to escape from them. This means you’ll still be gaining experience points, so you don’t want your characters to be too high level for this stretch.

If you’re able to defeat Great Joe and/or Mintia with their restrictions, then Albedo should be simple enough. I boosted MOMO’s Floral Tempest to level 11 to deal some good physical damage, and healed as needed. Under these circumstances, Albedo shouldn’t pose too much of a problem since his attacks don’t deal a lot of damage individually. The real concern is how he can increase his speed and get in loads of boosted turns, meaning those small attacks will rapidly build up if you don’t stay ahead of him.

Fission Fusion (10)

Defeat Sophie Peithos with chaos being the only one to make a move and using only ether and items (Level Limit: 46)

During this whole while, chaos has been in my party grinding for levels to earn one specific Ether spell called Cataclysm. To acquire it, unlock his Ether spell tree in this order, with the required Ether Points needed for each: Protective Wear -> Ice Wings (120 EP) -> Lightning Wings (280 EP) -> Cataclysm (620 EP). You have the option to spread out Cataclysm to your allies if you want to use it during other challenges.

Unfortunately, Cataclysm will not be doing an amazing amount of damage against the boss. Since you can’t use chaos’ Tech Attacks, this is your only real option for damage however, so this is going to slow and arduous. You are able to have your other two characters die during the battle if you only want to keep chaos alive. I would suggest holding out on this until the mooks that Sophie Peithos summons are all dead so that not all of their attacks will target chaos. Cataclysm does AoE damage, so with enough of them you will get rid of the lesser enemies eventually.

Sophie Peithos becomes terrifying when it starts using Dark Omen, which hurts everyone for around 700 damage. You have to keep chaos’ HP high at all times for this, and it becomes too much of a struggle to keep your other allies alive with Medica All when you just want to use Medica Rest on chaos. It doesn’t do the attack constantly, but it sort of falls into a pattern that you will be able to discern after a while. This is all about playing defensively and knowing when to use Cataclysm versus when to heal and use items. Keep tabs on the boss’ HP if you want to know where you’re at in the battle. The good news is that Sophie Peithos has no healing abilities. Just be patient, pay attention, and it will go down eventually.

CONCLUSION

That should be everything you need to know to accomplish Xenosaga Episode I’s missables in a sensible order. I was going into this blind and needed to do three playthroughs to cover everything, which was quite annoying for me. I intend on writing guides for the entire trilogy, so expect to see Xenosaga Episode II sometime soon. Until then, happy cheevo hunting!

  • Benit149, December 2025