Vitality is your health, and it is also the resource that blood magic is paid for with. The manual calls it your lifeblood.
Spending it
Spells are cast from the left hand by draining a portion of your vitality for each sigil committed. The Wizard Idol permanently reduces the vitality cost of casting a sigil, and several rings do the same.
Restoring it
Hearts dropped by defeated enemies restore vitality. A Fountain fully replenishes it in one touch. The Wiseman Idol permanently raises your maximum vitality.
Compiled from what this wiki already says on Spells, Rooms, Wizard Idol, Wiseman Idol, Hearts. No new facts were added.
From the official manual
- The manual describes the lifeblood meter as what you use for casting spells and for sustaining your vital functions, and says plainly that if it runs out, you die.
- It warns that committing a spell symbol costs a lot of lifeblood, so you should be ready to make the sacrifice before you start a spell.
The manual details above come from the official game manual, a primary source: the developer's own documentation rather than community research.
Sources and community notes
- A strategy guide advises casting only after a room is cleared and a blood-restoring fountain has been found, and to watch the meter carefully rather than risk ending a run on a spell.
Community-sourced (added October 2026, not yet verified in-game). Sources: Steam guide: How easly win almost all your runs by GettyX.