Bloodspell

You touch a creature within range and expend one of your unexpended Hit Dice. The creature regains Hit Points equal to the amount rolled.

Alternatively, you touch a creature that is not unconscious and have it expend its reaction and one of its unexpended Hit Dice. The creature regains Hit Points equal to the amount rolled.

Cantrip Upgrade. The amount of Hit Dice you or another creature can expend increases by 1 when you reach levels 5 (2), 11 (3), and 17 (4).