Venom Blade

You brandish the weapon used in the spell’s casting and make a melee attack with it against one creature within 5 feet of you. On a hit, the target suffers the weapon attack’s normal effects, and irremovable venom covers the target's wound until the start of your next turn. If the target is forced to make a Constitution saving throw, the target takes 1d8 poison damage as the venom seeps into the wound regardless of the result of the saving throw.

This spell’s damage increases when you reach certain levels. At 5th level, the melee attack deals an additional 1d8 poison damage to the target on a hit, and the poison damage the target takes from the venom increases to 2d8. Both damage rolls increase by 1d8 at 11th level (2d8 and 3d8) and again at 17th level (3d8 and 4d8).