Corruption.

You have been Corrupted. Part of your body has succumbed to the Corruption, and while still under your control, drains you of life slowly. Roll 1D6 necrotic damage every sunrise until you are dispelled of the Corruption. Gain the Abilities Leech, Wither, and Corrupting Touch

Casting each spell drains 5Hp from user  going up by 5 for each level higher cast