Grim Vitality

Prerequisite: None

Your body rejects natural healing, but you have mastered the art of sustaining yourself through unnatural means. You gain the following benefits:

• You cannot regain hit points from any source, including spells, potions, class features, or hit dice. However, you can still gain temporary hit points as normal.
• You have a pool of Grim Vitality charges equal to your proficiency bonus, which you regain after a short rest.
• As a bonus action, you can expend a charge to grant yourself temporary hit points equal to 2d4 
• When you hit a creature with a weapon or spell attack, you can use your bonus action to expend a charge, dealing necrotic damage equal to the temporary hit points you would have gained instead of gaining them.