Dross said:YMMV but the feat requires INT13, STR15, Combat Expertise, Imp Trip and BAB+3. That is a fair set of pre-reqs (not the hightest, but not the least eaither).
I personally think that the feat needs the damage required to be upped a bit (afterall by level 3 a fighter could be doing 10+ damage semi- to regually) or activated on a confirmed (or unconfirmed) crit.
I agree. I upped the damage required to 20 in my games after the party had a battle with the elite guards of one kingdom (they were all 6th level human fighters with WF: Glaive, Combat Expertise, Combat Reflexes, Improved Trip, Knockdown, WS: Glaive, Power Attack and Cleave with 16 Str and Glaives+1.) All they had to do was drop 1 point into Power Attack and they had an automatic Knockdown chance with every hit. It was ridiculous and no fun for the party.