You can instantly slay your favored enemies with a single strike.
Prerequisites: Bane of Enemies, Survival 30 ranks, five or more favored 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 + ½ 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: Standard Reference Document under Open Game License v1.0a, which updated this feat originally published in the Epic Level Handbook, page 52.