Angler Lord

Fish. The Angler Lord can only breathe in water.

Legendary Resistance (1/week). When the Angler Lord fails a saving throw, roll a d4. If you get a 3 or a 4, it can choose to succeed instead. If it decided not to succeed, or if it rolls a 1 or a 2, it keeps its Legendary Resistance for the next saving throw.

Lure. When someone sees the Angler Lord's light, they must make a DC 10 Wisdom saving throw. If the Angler Lord is in dim light or darkness, this becomes DC 15. On a failed save, the Angler Lord can mind control them to move towards it with their full movement speed as the entirety of their action. They can repeat the saving throw at the end of their turn to break free.

Suction. All characters in the water within 100 feet of the Angler Lord are pulled 1d6x5 feet closer to it.

Bite. Melee Weapon Attack: Always hits, reach 5 ft., unlimited targets. Hit: 41 (6d6 + 20) Piercing damage.

Absorb Elements. When hit by a Fire, Lightning, Cold, Acid, or Poison attack, its teeth absorb the energy for its next bite attack, causing its next bite attack to do 3d6 extra damage of the absorbed type, as well as causing a unique effect depending on the damage type. Fire does 4d6 extra instead of 3d6, Lightning causes Paralysis for 1 minute, Cold slows movement speed by 20 feet for 1 minute, Acid lowers AC by 5, and Poison causes Poison for 1 minute. For Paralysis, the target gets to make a DC 14 Constitution saving throw to avoid the effect, and can repeat the saving throw to end the effect on themselves at the start of each of their turns.