[Taqwus]

Experimenting Last night, it seemed to me that Wailing Ladies make a good chassis for assassins. Granted, only Ermor gets 'em...
...but they're stealthy (+0 only), ethereal, unholy, zero-enc, undead scary units with a length-6 area-1 save-or-die wailing attack, and they have all the usual equipment slots. Give one some armor (even a Marble Breastplate will help enormously), a Black Heart, perhaps boots of quickness and a luck charm, and go a-caroling.