Muraenid

Pack Tactics. Advantage on attacks vs. creature if 1+ unincapacitated attacker ally is within 5 ft. of target.

Speak with Aquatic Creatures. Communicate with Monstrosities and Beasts that have a swim speed as if they shared a language.

Water Breathing. Can breathe only underwater.

Bite. Melee Weapon Attack: +5 to hit, 5 ft., one target, 14 (2d10+3) piercing damage and the target is grappled (escape DC 13). Until grapple ends muraenid can Bite only the grappled creature and has advantage on attack rolls to do so.

Telekinetic Grip. One creature it can see within 60' of it must make DC 13 Str save or be moved up to 30' in a direction of muraenid's choice and be restrained until start of muraenid's next turn. If muraenid targets an object weighing 300 pounds or less that isn't being worn or carried object is moved up to 30' in a direction of muraenid's choice. Muraenid can also use this action to exert fine control on objects such as manipulating a simple tool or opening a door or a container.

Lord of the Fishes (1/Day). One Beast with swimming speed muraenid can see within 30' of it: DC 12 Wis save or be magically charmed by it for 1 day or until it dies or is more than 1 mile from target. Charmed target obeys muraenid's verbal or telepathic commands can't take reactions and can telepathically communicate with muraenid over any distance provided they are on same plane of existence. If target suffers any harm can re-save success ends effect on itself.