Crimson Avatar

Become a living vessel of blood magic. For the duration, you have resistance to necrotic damage, advantage on CON saves, and your Sanguinomancy powers ignore necrotic resistance from creatures with blood. Once per turn when a creature takes necrotic damage from your Sanguinomancy power, you gain temporary hit points equal to your WIS modifier.

This power has its own stable page so it can be linked from any character, item, location, story post, bargain, curse, or future reward.