taken the heart

You can use attack action and you can go through the creature chest and rip the heart out.

The target must make a constitution saving throw,on a failed save,it take 10d6 necrotic damage, or half as much damage on successful save,but if the creature fails,each round as a bonus action you can inflict 8d6 to see how much power that you can use to rip through the chest,if failed save,the 8d6 necrotic damage.if the target reaches 0 hit point,the heart bursts free from the chest.