Venom Strike

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 as well as those of a toxic venom causing the target's speed to be reduced by half until the start of your next turn.

At Higher Levels. At 5th level, the melee attack deals an extra 1d8 poison damage to the target on a hit. This damage increases by 1d8 at 11th level (2d8) and again at 17th level (3d8).