Full-Blooded (Grim Hollow)

Full Blooded School of Sangromancy class feat to track bonus hit die.
(Only works for single class Wizard)

"Full Blooded
Starting at 2nd level, you gain a pool of d12s that you can expend instead of a hit die when you cast sangromancy spells. The number of dice in the pool equals 1 + your wizard level.
Your pool regains all expended dice when you finish a long rest."