Player monsters, crossaligned priests, and hostile angels on the Astral Plane should be able to steal the Amulet from you. If they get it, they will try to make a beeline to their high altar to sacrifice it.

The player is also able to steal the Amulet back, though, and wearing the Amulet acts as one turn of protection against it being stolen: an attempt to steal it will just remove it from your neck.

If something else ascends, your game ends in an escape. However, the crowd of Astral monsters are hostile towards the Amulet-bearer, not you; so if it gets stolen from you, the pressure will let up a bit.