Big Bad Kubazon Stormeater

Amphibious. The froghemoth can breathe air and water.

Poisonous Skin. Any creature that grapples Kubazon or otherwise comes into direct contact with the Kubazon’s skin must succeed on a DC 18 Constitution saving throw or become poisoned for 1 minute. A poisoned creature no longer in direct contact with Kubazon can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success.

Stormbelly (Mythic Trait; Recharges after a Short or Long Rest).
If Kubazon is reduced to 0 hit points, she doesn't die or fall unconscious. Instead, he regains 136 hit points. In addition, his skin crackles with electrical energy granting him 50 temporary hit points and access to his Mythic actions. This transformation lasts until Kubazon finishes a short or long rest.

Multiattack. Kubazon makes two attacks with its tentacles. It can also use its tongue or bite.

Tentacle. Melee Weapon Attack: +10 to hit, reach 25 ft., one target. Hit: 19 (3d8 + 6) bludgeoning damage, and the target is grappled (escape DC 16) if it is a Huge or smaller creature. Until the grapple ends, Kubazon can’t use this tentacle on another target. Kubazon has four tentacles.

Bite. Melee Weapon Attack: +10 to hit, reach 5 ft., one target. Hit: 22 (3d10 + 6) piercing damage, and the target is swallowed if it is a Medium or smaller creature. A swallowed creature is blinded and restrained, has total cover against attacks and other effects outside Kubazon, and takes 15 (3d6) acid damage and 1d6 lightning damage at the start of each of Kubazon’s turns.

Kubazon’s gullet can hold up to two creatures at a time. If Kubazon takes 20 damage or more on a single turn from a creature inside it,  Kubazon must succeed on a DC 20 Constitution saving throw at the end of that turn or regurgitate all swallowed creatures, each of which falls prone in a space within 10 feet of Kubazon. If the Kubazon dies, a swallowed creature is no longer restrained by it and can escape from the corpse using 10 feet of movement, exiting prone.

Tongue. Kubazon targets one Medium or smaller creature that it can see within 30 feet of it. The target must make a DC 18 Strength saving throw. On a failed save, the target is pulled into an unoccupied space within 5 feet of Kubazon, and Kubazon can make a bite attack against it as a bonus action.

Storm Bellow. Kubazon explosively exhales causing all creatures within 30 feet must make a CON save DC 18 or become Deafened for one minute and Stunned for one round. Success on this save means they suffer none of the ill effects.

Lightning Lariat - Kubazon lurches up to half his movement forward with tendrils outstretched and can make a single Tentacle attack at each target within 10 feet along this path. In addition to the normal damage of his tentacles, the targets suffer an additional 2d4 lightning damage.

Thundering Storm Bellow - While Mythic, Kubazon's Storm bellow has a range of 60 feet and also forces any creature focusing on a spell to make a concentration check.