Terrifying Warrior

 
Prerequisite(s): Str 13+, BAB 3+, Cleave, Power Attack
 
Benefit: If you make an additional attack and drop that opponent with your cleave attack, all other opponents within reach must make a will save vs DC = 10 + 1/2 your lvl + your Cha modifier, or become panicked for 1d4 rounds. Foes with HD equal to or greater than yours are immune to this effect. This is an extraordinary mind-affecting fear effect.
 
Source: Dragon Magazine #343