Acidic Weapons. The acid spawn's attacks do 4 (1d8) extra damage on a failed DC15 Constitution save (included in attack)

Water Weakness. If the acid spawn touches magical or non-magical water it drops to 0 hit points and dies, leaving behind it's acid blade. It's acid blade counts as an normal longsword when it the acid spawn dies.

Multiattack. The acid spawn makes one acidic punch attack and one acid blade attack.

Acidic Punch. Melee Weapon Attack: +3 to hit, reach 5 ft.,  one target. Hit: 2 bludgeoning damage, plus the target must succeed on a DC15 Constitution save or take 4 (1d8) acid damage.

Acid Blade. Melee Weapon Attack: +3 to hit, reach 5 ft., one target. Hit: 6 (1d8 + 2) slashing damage, plus the target must succeed on a DC15 Constitution save or take 4 (1d8) acid damage.