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

Multiattack. Wulfharth makes one attack with his longsword, and then speaks with force.

Dragonbone Longsword. Melee Weapon Attack: +14 to hit, reach 5 ft. Hit: 18 (3d8 + 4) Slashing damage plus 28 (5d10) Fire damage.

Speak With Force. Constitution Saving Throw: DC 22, each creature in a 60-foot cone. Failure: 44 (8d10) Thunder damage. Success: Half damage.

Thu'um (Recharge 5-6). Wulfharth uses one of the following dragon shouts, using Constitution as the spellcasting ability (spell save DC 22, spell attack modifier +14):
Aura Whisper. Wulfharth gains the ability to sense creatures auras for 1 minute. He can detect any creature within 500 feet, even through walls or invisibility, although he only gets a vague sense of their shape and size.
Cyclone. Strength Saving Throw: each creature in a 20-foot wide and 150-foot long line. Failure: 54 (12d8) Bludgeoning damage, the target is thrown 80 feet into the air, and 40 feet in a random direction, landing Prone. Success: Half damage and the target is thrown 30 feet into the air, and 20 feet in a random direction.
Disarm. Strength Saving Throw: one creature Wulfharth can see within 300 feet. Failure: Any objects or creature the target is holding and grappling are thrust from their grasp. A held object flies 100 feet away in a random direction, and a grappled creature is knocked 10 feet away. Success: The target has disadvantage on attack rolls with any weapon held when hit until the end of their next turn. Any creature they are grappling had advantage on their next check to escape the grapple.
Dismay. Wisdom Saving Throw: each creature in a 80-foot cone. Failure: The target drops whatever it is holding and has the Frightened condition for 1 minute. A Frightened creature takes the Dash action and moves away from Wulfharth by the safest route on each of its turns unless there is nowhere to move. If the creature ends its turn in a space where it doesn’t have line of sight to Wulfharth, the creature makes a Wisdom saving throw. On a successful save, the effect ends on that creature. Success: The target has the Frightened condition for 1 minute, and rerolls the Wisdom saving throw at the end of each of it's turns. On a successful save, the effect ends on that creature.
Fire Breath. Dexterity Saving Throw: each creature in a 150-foot cone. Failure: 108 (24d8) Fire damage. Success: Half damage.
Frost Breath. Constitution Saving Throw: each creature in a 150-foot cone. Failure: 108 (24d8) Cold damage. Success: Half damage.
Slow Time. Wulfharth’s Speed is doubled, he gains a +2 bonus to Armor Class, has Advantage on Dexterity saving throws, and gains an additional action on each of his turns for 1 minute. That action can be used to take only the Attack (one attack only), Dash, Disengage, Hide, or Utilize action.
Unrelenting Force. Constitution Saving Throw: each creature in a 120-foot cone, a Construct has Disadvantage on the save. Failure: 94 (17d10) Thunder damage, the target is pushed 60 feet away from Wulfharth, and lands Prone. Success: Half damage and the target is pushed 20 feet away.
Whirlwind Sprint. Wulfharth moves up to 500 feet in a straight line without provoking attacks of opportunity and ignoring difficult terrain.

Counterattack. Trigger: Wulfharth is hit by an attack roll. Response: Wulfharth adds 4 to his AC against that attack, possibly causing it to miss. On a miss, he can make one Longsword attack against the attacker.

Legendary Action Uses: 3. Immediately after another creature’s turn, Wulfharth can expend a use to take one of the following actions. He regains all expended uses at the start of each of his turns.

Deep Breath. Wulfharth rolls to recharge his Thu'um.

Blade. Wullfharth moves up to half his Speed, and it makes one Longsword attack.