Captain Veldrin, Herald of Storms

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

Storm's Ascent. Captain Veldrin is immune to the negative effects of storm-like conditions, including wind, lightning, and non-magical thunder-based environments. Once per short rest, as a bonus action, Captain Veldrin can fly at twice his normal fly speed for 10 minutes.

Infused with the Storm. When reduced below 200 hit points, Captain Veldrin's body crackles with the power of the storm, increasing his damage output. His attacks deal an additional 4d10 lightning damage per strike, and enemies that end their turn within 10 ft. of him take 15 (3d10) thunder damage automatically.

Innate Spellcasting. Captain Veldrin’s innate spellcasting ability is Charisma (spell save DC 21). He can innately cast the following spells, requiring no material components:

At will: Gust of Wind, Lightning Bolt, Shield

3/day each: Call Lightning, Thunderwave

1/day each: Control Weather, Chain Lightning

Multiattack. Captain Veldrin makes three attacks: two with his Longsword of Roaring Skies and one with his Thunderclap Shotgun.

Longsword of Roaring Skies. Melee Weapon Attack: +13 to hit, reach 10 ft., one target. Hit: 24 (4d8+6) slashing damage plus 21 (6d6) lightning damage. On a critical hit, the force of the blow creates a sonic boom, forcing all creatures within 15 ft. to make a DC 21 Constitution saving throw or be deafened and knocked prone for 1 minute.

Thunderclap Shotgun. Ranged Weapon Attack: +12 to hit, range 30/90 ft., one target. Hit: 27 (4d10+5) thunder damage. Creatures hit by this attack must make a DC 20 Strength saving throw or be pushed 20 feet away from Captain Veldrin.

Stormstep (Recharge 4-6). Captain Veldrin can teleport to a location within 60 ft., leaving a surge of storm energy in his place. All creatures within 10 ft. of the teleportation origin must succeed on a DC 21 Dexterity saving throw or take 30 (6d10) lightning damage.

Dragon's Wrath (Recharge 5-6). Veldrin channels his blue dragon heritage to release a devastating lightning strike in a 60 ft. long and 5 ft. wide line. Each creature in that line must succeed on a DC 21 Dexterity saving throw, taking 72 (16d8) lightning damage on a failed save, or half as much on a successful one.

Captain Veldrin 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. Veldrin regains spent legendary actions at the start of his turn.

Detect. Captain Veldrin makes a Wisdom (Perception) check.

Lightning Slash. Captain Veldrin makes a melee attack using his Longsword of Roaring Skies.

Call Thunderstorm (Costs 2 Actions). Captain Veldrin calls upon the storm itself, causing lightning to arc in a 30 ft. radius centered on him. Each creature of his choice in the area must make a DC 21 Dexterity saving throw, taking 44 (8d10) lightning damage on a failed save, or half as much damage on a successful one.