Destruction Retribution
(Libris Mortis: The Book of the Dead, page 26, DnD 3.5)
[General]
Undead you raise or create harbor a retributive curse that is unleashed if they are destroyed.
Prerequisite
Benefit
Each undead you raise or create with any necromancy spell releases a burst of negative energy upon its destruction, dealing 1d6 points of damage plus an additional 1d6 points per 2 Hit Dice to every creature within a 10-foot spread (Refl ex DC 15 half). This damage comes from negative energy, and it therefore heals undead creatures