Please explain Heavy Punch use to me

[Hal900x]

I am not seeing the value in this feat. 200% cost for 180% damage. I have not actually ever tried this feat in any build, but my guesses would be: at low level when fist weapons have difficulty penetrating resistance or perhaps "charging up" the attack with another feat or some other type of buff before using Heavy Punch. I really can't see how it's worth taking with what I know now, perhaps someone else could enlighten me.

[DemoneNero]

If you use pneumatic gloves and have the combo feat that's the attack to use if the special hit (combo or pneumatic) triggers, if you manage to have both combo and pneumatic and use heavy punch in that attack you will get an insane damage spike 

[ciox]

Even before you can get more advanced gear and feats, I always thought it was supposed to be used in situations where the target was at some disadvantage (incapacitated = extra damage from opportunist feat, unaware = guaranteed crit) that would be removed if they were attacked, so heavy punch lets you get the most out of that.

[destroyor]

If you use pneumatic gloves and have the combo feat that's the attack to use if the special hit (combo or pneumatic) triggers, if you manage to have both combo and pneumatic and use heavy punch in that attack you will get an insane damage spike 

This is the correct answer.

However, there are tons of other more useful feats so the opportunity cost of taking heavy punch is too great. I wouldn't recommend taking heavy punch for any build.