Level
Cantrip
Casting Time
1 Action
Range/Area
Touch
Components
V, S
Duration
Instantaneous
School
Evocation
Attack/Save
None
Damage/Effect
Exhaustion
You channel the inner life force of a creature to cause a surge of natural healing. When touching a creature in range it can spend one of its Hit Dice and regains hit points equal to the amount rolled but gains one level of exhaustion.
A creature touched by this spell can spend one additional Hit Die when you reach 5th level (2), 11th level (3), and 17th level (4).
This spell looks great in situations where the DM approves of a healing cantrip, but wants it to come at a cost. I'd recommend adding details about how it brings back up a target who had 0 HP. Maybe the target would have to roll a constitution saving throw in order to be able to get back up their next turn, or stay down from the exhaustive nature of the spell.
I love it! I think if you are adding the cost of Exhaustion, it seems reasonable to allow the target to add it's constitution modifier. At higher levels, the modifier would only be added to the first die rolled.