Yavalnoi

Water Breathing. The yavalnoi can breathe only underwater.

Innate Spellcasting. The yavalnoi's innate spellcasting ability is Charisma (spell save DC 15). It can innately cast the following spells, requiring no material components. At will: ray of enfeeblement, silent image 3/day: control water, slow

Multiattack. The yavalnoi makes three attacks: one with its bite, one with its claw, and one with its tail.

Bite. Melee Weapon Attack: +6 to hit, reach 5 ft., one target. Hit: 14 (2d10 + 3) piercing damage.

Claw. Melee Weapon Attack: +6 to hit, reach 5 ft., one target. Hit: 7 (1d8 + 3) slashing damage.

Tail. Melee Weapon Attack: +6 to hit, reach 10 ft., one target. Hit: 10 (2d6 + 3) bludgeoning damage.

Luminous Burst (Recharge 5-6). The anchor-shaped organ atop the yavalnoi's head emits a burst of blue light. Each hostile creature within 30 feet of the yavalnoi must succeed on a DC 15 Wisdom saving throw or be outlined in blue light for 1 minute. While outlined in blue light, a creature can't breathe underwater. This effect dispels spells such as water breathing and temporarily suppresses water breathing granted through magic items or a creature's natural physiology. In addition, the yavalnoi and creatures friendly to the yavalnoi have advantage on attack rolls against creatures outlined in blue light. A creature outlined in blue light can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success.

Call of the Deep (1/Day). The yavalnoi magically calls 2d4 giant crabs or 1 giant octopus. The called creatures arrive in 1d4 rounds, acting as allies of the yavalnoi and obeying its spoken commands. The beasts remain for 1 hour, until the yavalnoi dies, or until the yavalnoi dismisses them as a bonus action.