If Astral denizens are able to steal the Amulet from you and try to ascend with it: The amulet-bearer uses a special AI algorithm which pathfinds towards their high altar, using a shortest-path algorithm that avoids monsters if possible but if none are available will plot a path that goes through the minimum amount of monsters. They will only attack when the next square on their path is occupied by a monster, and they will only attack that monster.