Venom Fang Blade

You brandish the weapon used in the spell’s casting, magically imbuing it with deadly poison, 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. On a failure, the creature takes poison damage equal to your spellcasting ability modifier at the end of it's next turn.

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, and the poison damage from a failed save increases to 1d8 + your spellcasting ability modifier. Both damage rolls increase by 1d8 at 11th level (2d8 and 2d8) and 17th level (3d8 and 3d8).