Breath of Unlife
(Dragons of Faerun, page 47, DnD 3.5)
[Metabreath]
Your breath weapon contains the chill of undeath.
Prerequisite
charisma 13, Energy Breath weapon, undead
Benefit
Your breath weapon deals half damage of the normal type, and half negative energy damage agains living creatures. You Energy breath weapon deals normal energy damage agains Undead. In addition, you can take other Metabreath Feats (out of Draconomicon) as if you had a constitution score equal to your charisma