Azurian, the Lord of the Currents

Amphibious. Azurian can breathe air and water.

Legendary Resistance (3/Day). If Azurian fails a saving throw, he can choose to succeed instead.

Riparian Weapons. Azurian's weapon attacks are magical. When Azurian hits with his longsword, the weapon deals an extra 14 (4d6) cold damage (included in the attack).

Multiattack. Azurian makes three attacks: one with his longsword and two with his flood blast.

Longsword. Melee Weapon Attack: +10 to hit, reach 5 ft., one target. Hit: 15 (2d8 + 6) slashing damage plus 14 (4d6) cold damage.

Flood Blast. Ranged Spell Attack: +8 to hit, range 120 ft., one target. Hit: 21 (6d6) cold damage, and the target must succeed on a DC 18 Strength saving throw or be pushed up to 30 feet away from Azurian and knocked prone.

Grasping Whirlpool (Recharge 5-6). Azurian creates a 20-foot-radius, 30-foot-high cylinder of swirling water centered on a point he can see within 120 feet of him. Each creature in the cylinder must make a DC 18 Strength saving throw. On a failed save, a creature takes 36 (8d8) bludgeoning damage and is restrained by the swirling water. On a successful save, the creature takes half as much damage and isn't restrained. While restrained, a creature is unable to breathe unless it can breathe water, and it must succeed on a DC 18 Strength saving throw at the end of each of its turns or take 18 (4d8) bludgeoning damage. A creature, including the restrained creature, can take an action to free the restrained creature by succeeding on a DC 18 Strength check. A creature with a swimming speed has advantage on the saving throw and on the Strength check to escape. The whirlpool lasts for 1 minute or until Azurian dismisses it (no action required).

Spellcasting. Azurian casts one of the following spells, requiring no material components and using Charisma as his spellcasting ability (spell save DC 16):

At will: create or destroy water, water breathing

3/day each: freedom of movement, control water

1/day: control weather (as an action)

Blade Current. When a creature within 5 feet of Azurian misses him with a melee attack, Azurian can use his reaction to make a longsword attack against that creature.

Azurian can take 3 legendary actions, choosing from the options below. Only one legendary action option can be used at a time and only at the end of another creature's turn. Azurian regains spent legendary actions at the start of his turn.

Attack. Azurian makes one longsword or flood blast attack.

Flow. Azurian moves up to his walking speed, or swims up to half his swimming speed, without provoking opportunity attacks.

Ripple (Costs 2 Actions). Azurian causes a ripple of magical water to surge out from him. Each creature of his choice within 20 feet of him must succeed on a DC 16 Strength saving throw or be knocked prone and pushed 10 feet away from him. Until the start of Azurian's next turn, attack rolls against him have disadvantage.