Xanathar's Guide to Everything, Page 169

Toll the Dead

0-level (Cantrip) Necromancy

You point at one creature you can see within range, and the sound of a dolorous bell fills the air around it for a moment. The target must succeed on a Wisdom saving throw or take 1d8 necrotic damage. If the target is missing any of its hit points, it instead takes 1d12 necrotic damage.
 
At higher levels: The spell's damage increases by one die when you reach 5th level ( 2d8 or 2d12 ), 11th level ( 3d8 or 3d12 ), and 17th level ( 4d8 or 4d12 ).