Simbul's Synostodweomer

Source: Forgotten Realms - Heroes of Faerun

Level 7 Transmutation (Sorcerer, Wizard)
Casting Time: Action
Range: Touch
Components: V, S
Duration: 1 hour

You imbue one creature you touch with magical healing energy for the duration. Whenever the target casts a spell using a spell slot, the target can immediately roll a number of unexpended Hit Point Dice equal to the spell slot’s level and regain Hit Points equal to the roll’s total plus your spellcasting ability modifier; those dice are then expended.