Thekno's Heart

A wave of darkness and craziness blasts from the heart in a 15-foot cone. Each creature in that area must make a Intelligence saving throw, taking 1d8 necrotic damage and 1d8 radiant damage in a failed save, or half as much in a successful one.

The darkness necroses nonmagical life that aren't being worn or carried, also leaving voices for a while.

At Higher Level. When you cast this spell using a spell slot of 2nd level or higher, the damage increases by 1d8 necrotic damage for each spell slot above 1st.