Betsubrat

Volcanic Amphibian. The Betsubrat is immune to environmental damage that a volcano could cause e.g. magma/lava streams, heated earth, extremely high air temperature.

Charge. If the Betsubrat moves at least 20 feet straight toward a target then hits it with a tusk attack on the same turn, the target takes an extra 7 (2d6) slashing damage. If the target is a creature, it must succeed a DC 13 Strength saving throw or be knocked prone.

Rally to Mama. Betsubrats usually will gang up on the creature that their parent (a Betsubra) attacks. If not, they will attack who they deem to be the easiest targets, such as the back-liners (archers, mages etc.).  

Multiattack. The Betsubrat makes two attacks with its claws, or just one with its tusks and one discharge, or two discharges. (discharge has to be ready in order for it to be used in the multiattack, obviously)

Claws. Melee Weapon Attack: +5 to hit, reach 5 ft., one target. Hit: 13 (1d8 + 5) slashing damage.

Tusks. Melee Weapon Attack: +5 to hit, reach 5 ft., one creature. Hit: 13 (2d6 + 2) piercing damage

Discharge (Recharge 4-6). The Betsubrat spits a small gunk of lava-y mucus at a creature it can see within 70 feet of it. The creature must take a DC 14 dexterity saving throw, taking 24 (6d8) fire damage on a failed save or half as much on a successful one.