Cleave

You can drop multiple enemies with a single sweeping attack. 

Prerequisites: BCB +1, Strength 13

Benefit: If you drop a creature or confirm a critical with a two handed slashing or bludgeoning weapon, you can spend a reaction to make an immediate melee attack against a creature within reach.

The extra attack is with the same weapon and at the same bonus as the attack that dropped the previous creature. You can use this feat multiple times per round, provided you have sufficient reactions.

You can also use one more reaction each round. You can never have more reactions than your Dex bonus + 1.