A Transcendent Feat, Transcendence, and at least one Ability Score above 20
You can take an extra action, bonus action, and/or reaction once per turn each. When you use this ability, roll a hit die. You lose a number of hit points equal to your roll and your hit point maximum is lowered by the same amount.
The number of dice you roll increases by 1 for every time this ability is used. Your hp max and number of dice rolled both reset when you finish a long rest.