Your extended exposure to cosmic and nuclear waste has permanently altered your biology, turning what should be a lethal dose of radiation into a protective shield.

Your flesh and spirit carry the unique, lingering spark of necrotic energy that defines ghoulish existence. This dark saturation acts as a natural buffer, allowing you to easily withstand the draining forces of decay, death, and desiccation that would instantly wither a normal mortal. 

Vitality Retention: Your maximum hit points cannot be reduced by necrotic energy or curses.

The necrotic and toxic energies that rot the bodies of living creatures act as fuel for your unique metabolism. Instead of tearing your cells apart, these forces knit your dead flesh back together, accelerating your cellular regeneration mid-combat.

Toxic Rejuvenation: When you take poison or necrotic damage, you roll no damage dice. Instead, you instantly regain hit points equal to twice your proficiency bonus. You can use this feature a number of times equal to your Constitution modifier (minimum of once), and you regain all expended uses when you finish a long rest.