Help on: spell sentinel

A necromancer of level 9 or higher can use this spell to summon a phantom to watch a room. The phantom will hide in the room where summoned, during which time it will inform the caster if any players or creatures pass by or attack it. A necromancer can only have one phantom at a time; casting this spell will destroy any previously summoned phantom. Phantoms summoned through this spell remain for a day or more, depending on the level of the caster.