Necrotic Detonation

Your insight into undead allows you to weave a terrible curse into each undead you create or raise.  When an undead with this curse is destroyed or reduced to 0 hit points, it releases a burst of Necrotic energy that hits all creatures within a 10-foot radius.  Undead creatures within this radius, whether hostile or friendly, are immune to the detonation and are not healed by it.  The burst does 1d6 points of Necrotic damage, with a Dexterity save DC 15 for half damage.  Undead that release this Necrotic burst are utterly destroyed, this destruction does not release a second burst.  Undead that are under your control, but were not created or raised by you are not affected by this feat.