Spellcasting.

Death Burst. When the mephit dies, it explodes in a burst of acid. Each creature within 5 feet of it must make a DC 11 Dexterity saving throw, taking 7 (2d6) acid damage on a failed save, or half as much damage on a successful one.

False Appearance. While the mephit remains motionless, it is indistinguishable from an ordinary puddle of acid.

Innate Spellcasting. (4/Day). The mephit can innately cast acid splash whith a DC of 10. Its innate spellcasting ability is Charisma.

Slap. Melee Weapon Attack: +3 to hit, reach 5 ft., one creature. Hit: 3 (1d4 + 1) bludgeoning damage plus 2 (1d4) acid damage.

Acid Breath (Recharge 6). The mephit exhales a 15-foot cone of acid. Each creature in that area must make a DC 11 Dexterity saving throw, taking 7 (2d6) acid damage on a failed save, or half as much damage on a successful one.

Acidic Body: When directly hit by a non-magical attack (unarmed strike, sword, great axe, swung javelin etc.), the attacker must roll a Dex saving throw DC 12. On a failed save the attacker takes 2d4 and have the poised condition applied. (bows, crossbows, thrown javelins do not apply)