Camouflage was a magic spell available before the good and evil magic spellbooks were merged into one magic spellbook. The spell was cast on oneself, with no exterior target. The effect of the spell was to reduce the aggressiveness of NPCs against the casting player.
This spell was taken out before the formal release of Prayer. If it were to have remained in the game, this spell would likely have been moved to the Prayer book, along with other time-based, reflexive magic.