Once per battle, as a free action, you can make a standard melee attack after having dropped any enemy to 0 hp with a standard melee attack. Mooks do not count for this, unless the mook you dropped was the last of its mook mob.
You gain a +2 attack bonus with Barbaric Cleave attacks. If the cleave attack hits, you can heal using a recovery.
If there is no foe engaged with you to use your Barbaric Cleave attack against, as a free action you can move to a nearby foe before making the attack.
While raging, you can use Barbaric Cleave as many times as you like during a battle, but only once per round.