Master Hunter

A ranger of 20th level becomes a master hunter. He can, as a standard action, make a single attack against a favored enemy at his full attack bonus. If the attack hits, the target takes damage normally and must make a Fortitude save or die. The DC of this save is equal to 10 + 1/2 the ranger's level + the ranger's Wisdom modifier. A ranger can use this ability five times per day, but not against the same creature more than once in a 24-hour period.