Bub

Charge. If Bub moves at least 15 ft. straight toward a target
and then hits it with a slam attack on the same turn, the target takes
an extra 13 (2d12) extra damage per 15ft it flies, in a straight
motion, it deals an extra d12 damage and the dc increases by
two. If the target is a creature, it must succeed on a DC 21
Strength saving throw or be knocked prone.

Innate Spellcasting. Bub's innate spellcasting ability is Con
(spell save DC 22, [XON ATK] to hit with spell attacks). It can
innately cast the following spells, requiring no material
components:
At will: Gust of wind, thunderwave

Repulsive healing. When the Bub hits with an Prehensile Probiscis attack, it heals
double the amount of damage to itself if its under half of its
max hp

Corrosive organs. when Bub reaches 1/4th of its max hp, they begin leaking acidic blood from further wounds, attackers must make a DC 22, con save or take 2d4 acid damage upon physical attacks.

Prehensile Probiscis. Melee Weapon Attack: +9 to hit, reach 10 ft., one creature. Hit: 11 (2d6+4) piercing damage.

Slam. Melee Weapon Attack: +9 to hit, reach 5 ft, 1 target, Hit:  20(2d12 + 7) [Bludgeoning] damage.