Summon Greater Demon

Level: 4th
School: Conjuration
Casting Time: 1 action
Range: 60 feet
Components: V, S, M (a vial of blood from a humanoid killed within the past 24 hours)
Duration: Concentration, up to 1 hour

Description:

You summon a demon from the abyss. Choose a demon of challenge rating 5 or lower, such as a shadow demon or a barlgura. The demon appears in an unoccupied space you can see within range, and the demon disappears when it drops to 0 hit points or when the spell ends.

Roll initiative for the demon, which has its own turns. When you summon it and on each of your turns thereafter, you can issue a verbal command to it (no action required by you), telling it what it must do on its next turn. If you don’t issue any commands, the demon spends its turn attacking any creatures within reach that have attacked it. At the end of each of the demon’s turns, it makes a Charisma saving throw. The demon has disadvantage on this saving throw if you say its true name. On a failed save, the demon continues to obey you. On a successful save, your control over the demon ends for the rest of the duration, and the demon becomes hostile to you and your companions. A demon controlled in this way will not willingly return to the Abyss.

At Higher Levels:

When you cast this spell using a spell slot of 5th level or higher, the challenge rating increases by 1 for each slot level above 4th.

Notes:

• Control: The demon follows your verbal commands, but it can break free with a successful Charisma saving throw.
• Hostility: If the demon breaks free, it becomes hostile and may attack you or your allies.
• True Name: Knowing the demon's true name gives you an advantage in controlling it.

Source: Xanathar's Guide to Everything