Nexus Clash

Child skill of Feeding Fangs. The Revenant may drain the blood of a fresh corpse and gain a Bottle of Fermented Blood*. Bottles of Fermented Blood restore 6 HP (bonuses to healing from Mantle/Hunger of Vrykokalas also apply, so up to 10 healing at ≤25% HP with all relevant skills) and grant effects based on the drained corpse's class (seen in parentheses in the Revenant's inventory). Randomly-found bottles lack effects but still heal. Bodies can't be drained more than once and the drained corpse is no longer considered "fresh" (i.e. no Desecration or writing in blood).

*(except for Wyrm Masters of course, which produce a Vial of Acid)

Good idea
Would add that liches/revenants and possibly seraphs/VWs aren't fleshy and shouldn't have blood to be drained.

Seraphs could give an Oil of Holiness. Gotta have something keeping those mechanical bits from locking up.