Staff of the Arch-Vile.
Resurrects a corpse of your choice within LoS.  Makes you tired.  The resurrected monster will fight other monsters, will not attack you, and will generally try to follow you/stick near you.  Will not follow you down the stairs.  You cannot give it commands.  Resurrecting a monster costs HP:
Former human, sgt, imp, demon: 5hp
Captain,  Cacodemon: 10 HP
Hellknight, Commando: 20 HP
Baron of Hell, Mancubus, Arachnotron: 50 HP
Arch-Viles, Pain Elementals, Revenants, Uniques:  Cannot be resurrected.
Max 3 slaves at a time per level.   
Pick up Quote: Rise from your grave.