You shroud your hand, a weapon you are holding, or a natural weapon in dark ichorous miasma. The next time you hit a creature with a melee attack (including a melee spell attack) before the start of your next turn, the attack deals an extra 1d12 poison damage and the target must succeed on a Constitution saving throw or be poisoned until the end of your next turn.
The spell ends after dealing damage, or at the start of your next turn, whichever occurs first.