Oozing Mace (Patreon)

Weapon (mace), very rare

This mace is coated in a swirling mass of black ooze. You gain a +1 bonus to attack and damage rolls made with this magic weapon, which deals an extra 1d6 acid damage to any target it hits.

Corroding Slime. If you roll a 5 or 6 on the acid's damage die, the ooze latches onto the target, dealing an extra 1d6 acid damage to it and reducing its AC by 2. This penalty lasts until the start of your next turn, during which time the mace doesn't deal its extra acid damage to targets hit by it. The ooze magically returns to the mace at the start of your next turn.

Smack! Splat! SSSsssSSSsss.