Glutton for Punishment

Whenever you take damage from a weapon, spell attack, or an effect; you can roll 1d4 to add that total to the damage taken, you can add additional d4 (maximum your Constitution Modifier). After you take damage you gain a Punishment Die (1d6), you can only gain Punishment Die if you roll the 1d4 to add to the total damage. You gain additional Punishment Die equal to the additional d4(s) you added. The total amount of Punishment Die you can gain is equal to your Proficiency Bonus + your Constitution Modifier.

When you deal damage with a weapon or spell attack you can expend any amount of Punishment Die to add to the damage.