As an action, make a weapon attack.

On a hit, add 2d8 + your spellcasting ability poison damage to the attack’s damage roll and the creature must succeed on a Fortitude saving throw or it is poisoned for the duration.

On a critical hit, add twice as much damage.

On a miss by 4 or less, add half as much damage.

The creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success.

Augment

You can increase the damage by 3d8 for each additional mana expended.