Envenomed 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 must make a Constitution saving throw against the magical poison coating your weapon. On a failed save, the target has disadvantage on all ability checks made before the end of its next turn as its body struggles to fight off the magical toxins.

This spell’s damage increases when you reach certain levels. At 5th level, the melee attack deals an extra 1d8 poison damage to the target on a hit. The damage increases by 1d8 at 11th level (2d8) and 17th level (3d8).