Archdemon Vaelshrath, the malestrom

Storm Aura

Valsherath is surrounded by a swirling storm of corrupted energy in a 30-foot radius.

- When a creature starts its turn within this aura, it must succeed on a DC 20 Constitution saving throw or take 18 (4d8) lightning damage and 18 (4d8) necrotic damage.
- Ranged weapon attacks against Valsherath have disadvantage while she is within the aura.

Blight Infusion

Valsherath’s melee attacks deal an additional 14 (4d6) necrotic damage. Creatures hit must succeed on a DC 20 Constitution saving throw or gain 1 level of exhaustion.

Siege Monster,

Valsherath deals double damage to objects and structures.

Legendary Resistance (3/Day)

If Valsherath fails a saving throw, she can choose to succeed instead.

Actions

Multi attack

Valsherath makes three attacks: one with her bite and two with her claws.

Bite

Melee Weapon Attack: +14 to hit, reach 15 ft., one target.
Hit: 36 (5d10 + 8) piercing damage, plus 14 (4d6) lightning damage.

Claw

Melee Weapon Attack: +14 to hit, reach 10 ft., one target.
Hit:  28 (4d8 + 8) slashing damage, plus 10 (3d6) necrotic damage.

Maelstrom Surge (Recharge 5–6)

Valsherath unleashes a massive storm of corrupted energy. Each creature within 120 feet must make a DC 20 Dexterity saving throw.

- On a failure, a creature takes 45 (10d8) lightning damage and 45 (10d8) necrotic damage and is knocked prone.
- On a success, a creature takes half damage and isn’t knocked prone.

Call of the Swarm (1/Day)

Valsherath summons 3d4 Blighted Storm Drakes (CR 5) and 2d6 Darkspawn Corrupted Berserkers (CR 3) to aid her. They appear in unoccupied spaces within 60 feet of her and act immediately after her in initiative order.

Legendary Actions

Valsherath can take 3 legendary actions, choosing from the options below. Only one legendary action can be used at a time, and only at the end of another creature’s turn. She regains spent legendary actions at the start of her turn.

Wing Attack (Costs 2 Actions)
Valsherath beats her massive wings. Each creature within 15 feet must succeed on a DC 20 Dexterity saving throw or take 19 (3d6 + 8) bludgeoning damage and be knocked prone. Valsherath can then fly up to half her flying speed without provoking opportunity attacks.

Tail Swipe
Melee Weapon Attack: +14 to hit, reach 20 ft., one target.
Hit: 23 (3d8 + 8) bludgeoning damage.

Blighted Bolt
Valsherath fires a bolt of corrupted lightning at one creature within 120 feet. The target must make a DC 20 Dexterity saving throw or take 27 (6d8) lightning damage and 27 (6d8) necrotic damage.

When Valsherath is reduced to 0 hit points, it does not die. Instead, it unleashes a mythic transformation, regaining 150 hit points. During this phase:

• Its Storm Breath recharges automatically each round.

• It gains two additional legendary actions per turn.

• The Storm Sovereign aura extends to 60 feet and deals an extra 20 (4d10) force damage.

• Its melee and spell attack rolls have advantage.