Building Frenzy

Effect: 

One battle per day, as a free action after you have missed an attack, gain +1d4 damage to each successful melee attack until the end of the battle. For each missed attack following this, add another +1d4 damage, up to a maximum of +4d4 damage.

Adventurer Feat: 

Bonus damage dice are now d6s.

Champion Feat: 

Bonus damage dice are now d10s.

Epic Feat: 

You can use Building Frenzy twice a day.