Amphibious. Zal Ak can breathe air and water.

Tentacleton Summoner (3/Day). Zal Ak, three times a day can summon 1d4 worth of Tentacleton. They spawn within 10ft away from him. (For Tentacleton look at my DND Beyond Page)

Multiattack. The Zal Ak can attack with its claw once and its tentacle two times or it can use its growl once and its claw once.

Claw. Melee Weapon Attack: +5 to hit, reach 5 ft., one target. Hit: 13 (3d6 + 4) slashing damage. 

Tentacle. Melee Weapon Attack: +5 to hit, reach 20 ft., one target. Hit: 19 (3d10 + 4) bludgeoning damage.

Growl. All creatures (that are not Zal Ak or summoned by him) within a 150 ft. radius must succeed on a DC 15 Wisdom saving throw, if they fail then that take Hit: 20 (3d12 + 2) worth of damage and their AC's are reduced to half (rounded up) until Zal Ak takes his next turn.

Living Lightning Rod. When Zal Ak gets hit by a lightning attack in water, instead of taking double the damage he can take quadruple the damage but then can electrocute the body of water he is in dealing the same damage he took, this attack does not effect him or the Tentacletons.