Canker

A green ghastly light emanates from the spellcaster and transfers onto the target at touch focusing in to a brighter point upon the point touched on the target.  

Target must succeed on a DC 17 Constitution saving throw or be infected with a cankerous wound. The wound deals 1d6 necrotic damage at the start of each of the target's turns until the target receives magical healing or finishes a long rest

This spell's damage increases by 1d6 when you reach 5th level (2d6), 11th level (3d6), and 17th level (4d6).