Gruesome Finish

 
Prerequisite(s): Base Attack Bonus 6+.
 
Benefit: Whenever you make a full attack and reduce an opponent to 0 or fewer hit points, you can give up any remaining attacks you have in a round to force the target to make a Fortitude save (DC 10 + 1/2 your level + your Cha modifier). If the target fails the save, he dies instead of becoming disabled, and all creatures within 30' must succeed on a Will save against the same DC or become sickened for 1 round.
 
Special: You can use this feat only if you still have one or more attacks left in a round after reducing your target to 0 or fewer hit points.
 
Source: Exemplars of Evil