Pass without Trace (Illusion)
Level: Druid 1, Ranger 1, Assassin 2
Mana: 5. Persistant. Base Success: 100%.
  Turns your party effectively invisible on the wilderness screen -- encounters will not chase you, and even if you bump into one, you have a 50% chance of being able to decide whether you want to evade it or not. Additionally, you cannot be sensed by creatures using Scent, Tremorsense or Tracking.