Caustic Curse

The caster cuts their hand letting blood well up taking 1d6 damage. The blood can be smeared onto a weapon or diffused upon expending a spell. The victim must make a constitution saving throw or be poisoned, taking 3d6 poison damage.

Every round the victim can make a new Con save, if successful they shrug off the poisonous effects. If not, they take additional 1d6 damage. They can also be cured via lesser restoration. 

At Higher Levels. When you cast this spell using a spell slot of 3rd level or higher, the damage increases by 1d6 for each slot level above 2nd.