Sylvan's Volatile Bolt

You pour water and oil into your dart, the pure energy of unstable magic turns it instantly into vapor and arcane energy. Your next ranged attack is involved by this erratic power and deals an extra 2d6 force damage to the target. On a critical success, you hit a weak point of the creature and the pain from the arcane mess is nearly unbearable, the next attack roll against the creature has advantage. If you get a critical failure on the attack, the chaotic energy rebels and deals 1d8 force damage to the caster.

At Higher Levels. When you cast this spell using a spell slot of 2nd level or higher, the extra damage increases by 1d6 by  for each slot level above 2nd.