Blood Engine

Driven by aggression and sustained by slaughter, your systems run on every drop of spilled blood as sustenance for function.

• When you reduce a creature to 0 hit points with a weapon attack within 60 feet, you regain hit points equal to 1d4 + your proficiency bonus.
• When you score a critical hit against a creature within 60 feet, you regain hit points equal to 1d4 + your proficiency bonus.

 Creatures you attack must have blood to trigger the benefits of this feat. 

"He who taketh not up arms shall not draw breath. Go forth, ye ironborn, and prove thy worth to endure. Thou art engines of war, and blood is thy fuel." - Archfiend Atikah, Lord of Battle