Venomous Steel

Your weapon is coated in poison.  As part of the action used to cast this spell, you must make a melee attack with your weapon against one creature within the spell's range, otherwise the spell fails.  On a hit, the target suffers the attack's normal effects plus an extra 2d8 poison damage.  Additionally, the target must succeed on a Constitution saving throw or be poisoned until the spell ends.

A creature poisoned by this spell makes another Constitution saving throw at the end of each of its turns. On a successful save, it is no longer poisoned.

At Higher Levels. When you cast this spell using a spell slot of 4th level or higher, the extra damage increases by 1d8 for each slot level above 3rd.