Deadly Weapon Dance

You've learned to flow with your weapon, letting its momentum quicken your strikes. You gain the following benefits:

• On your turn, when you score a hit with a melee weapon, you can roll damage or you can choose to roll a D20. If you roll a 15-20, you successfully hit with the same melee weapon again, though the damage die goes down (ex: from a D10 to a D8). You can continue chaining the attacks together until you reach a D4, adding the damage for each successful hit. If you roll a D20 and do not get a 15-20, all attacks in the chain miss. 
• If you score a critical hit, you automatically succeed on the first chained attack. Damage dice are doubled only on the hit where the 20 occurred.