Cell Decomposition

You touch a creature or object and cause its cells to rapidly age and decompose. At the end of each of your turns, the target takes 1d6 necrotic damage, and, on their turn, they may roll a Constitution saving throw to stop the cells from decomposing any further.

Optionally (to the DM), since affected cells actually fall off and die, only when the decomposed parts are mended to the affected areas are they allowed to be healed, and then, they can only be healed by magical means.

At Higher Levels. When you cast this spell using a spell slot of 2nd level or higher, the amount of damage it deals increases by 1d6 per level over 1st.