Death of Enemies

 
Prerequisite(s): 21+ level, Survival 30+ ranks, five or more favored enemies, Bane of Enemies
 
Benefit: Any time the character scores a critical hit against one of his or her favored enemies, it must make a Fortitude save (DC 10 + 1/2 character’s ranger class level + character’s Wisdom modifier) or die instantly.
 
Special: Creatures immune to critical hits can’t be affected by this feat.
 
Source: Epic Level Handbook