Black Blood

Black Blood is a boss relic exclusive to the Ironclad. It replaces the starter relic Burning Blood and heals the Ironclad for 12 HP at the end of each combat, instead of the original 6 HP. It is automatically obtained when the Ironclad defeats the Act 1 boss, upgrading the character's inherent sustain ability.

Black Blood doubles the Ironclad's natural healing rate, making it significantly easier to maintain high health throughout a run. The 12 HP per combat adds up to substantial total healing across an entire run and reduces reliance on rest sites, freeing those stops for upgrades or other choices. Black Blood is especially valuable on aggressive or risky builds that frequently take damage while dealing large amounts, and it synergizes with cards like Offering and Rupture that trade HP for power. The larger heal also extends the viability of strategies that intentionally run at low HP. While Black Blood cannot be refused (it replaces Burning Blood automatically), this automatic upgrade is universally desirable and makes the Ironclad one of the most resilient characters in longer runs.