You can make a Whirlwind attack as the first action of your turn when you are engaged by two or more enemies.

You take a –4 penalty to your AC and PD until the start of your next turn. Then roll a separate melee attack against each enemy you are engaged with. You deal no miss damage with these attacks.

Adventurer Feat: 

You now deal normal miss damage with missed Whirlwind attacks.

Champion Feat: 

The penalty to your AC and PD is reduced to –2. In addition, disengage checks you make the same turn as using Whirlwind automatically succeed.

Epic Feat: 

You can use Whirlwind anytime during your turn, not just as the first action.