Venomous Blade

As part of the action used to cast this spell, you must make a melee attack with a weapon against one creature within the spell's range, otherwise the spell fails. On a hit, the target suffers the attack's normal effects, and is inflicted with a harsh poison. The melee weapon attack deals an additional amount of poison damage equal to your spellcasting modifier. Additionally, at the start of the target's turn, they must make a Constitution saving throw against your spell save DC or take 1d8 poison damage.

The spell's damage increases when you reach higher levels. At 5th level, the melee attack deals an additional 1d8 poison damage and the poison damage taken for failing the saving throw increases to 2d8. Both damage rolls increase by 1d8 at 11th level and 17th level.