Great Weapon Master

You’ve learned to put the weight of a weapon to your advantage, letting its momentum empower your strikes. You gain the following benefits:

• On your turn, when you score a critical hit with a melee weapon or reduce a creature to 0 hit points with one, you can make one melee weapon attack as a bonus action.
• Before you make a melee attack with a heavy weapon that you are proficient with, you can choose to take a -X penalty to the attack roll. If the attack hits, you add +X*2 to the attack’s damage.