Belthoryx

Death Throes. The balor explodes when it dies. Dexterity Saving Throw: DC 20, each creature in a 30-foot Emanation originating from the balor. Failure: 31 (9d6) Fire damage plus 31 (9d6) Force damage. Success: Half damage. Failure or Success: If the balor dies outside the Abyss, it gains a new body instantly, reviving with all its Hit Points somewhere in the Abyss.

Fire Aura. At the end of each of the balor’s turns, each creature in a 5-foot Emanation originating from the balor takes 13 (3d8) Fire damage.

Epic Boss Hit Points. Increase Belthoryx's starting hit points and hit dice by 250 (20d12 + 140) for each player character above four, or reduce its starting hit points and hit dice by that amount for each player character below four.

Immutable Form. The Belthoryx is immune to any spell or effect that would alter its form.

Legendary Resistance (3/Day). If the balor fails a saving throw, it can choose to succeed instead.

Magic Resistance. The balor has Advantage on saving throws against spells and other magical effects.

Multiattack. The balor makes one Flame Whip attack and one Lightning Blade attack.

Flame Whip. Melee Attack Roll: +16, reach 30 ft. Hit: 18 (3d6 + 8) Force damage plus 17 (5d6) Fire damage. If the target is a Huge or smaller creature, the balor pulls the target up to 25 feet straight toward itself, and the target has the Prone condition.

Lightning Blade. Melee Attack Roll: +16, reach 10 ft. Hit: 21 (3d8 + 8) Force damage plus 22 (4d10) Lightning damage, and the target can’t take Reactions until the start of the balor’s next turn.

Teleport. The balor teleports itself or a willing demon within 10 feet of itself up to 60 feet to an unoccupied space the balor can see.

Aura of Fallen Champions (Recharge 5–6). Belthoryx unfurls his wings and chains, summoning spectral flames and the spirits of slain champions around him in a 30-foot radius until the start of his next turn.

• Enemies inside the aura have disadvantage on attack rolls against Belthoryx.

• Belthoryx has advantage on attack rolls against enemies inside the aura.

• Belthoryx has advantage on all saving throws while the aura is active.

• Enemies inside the aura have disadvantage on all saving throws.

This is not a spell.

Legendary Actions. Belthoryx 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.

Whip Attack. Belthoryx makes one Flame Whip attack.

Cast a Spell (Costs 2 Actions). Belthoryx casts one of his innate spells.

Arena’s Grasp. Belthoryx calls upon the arena’s spirits. Each enemy within 30 feet must succeed on a DC 20 Strength saving throw or become Restrained until the end of their next turn.

Innate Spellcasting (Save DC 20, +12 to hit). Belthoryx’s spellcasting ability is Charisma. He can innately cast the following spells, requiring no material components:

• At will: Detect Magic, Teleport

• 3/day each: Fireball (5th level), Lightning Bolt (5th level)

• 1/day each: Forcecage, Delayed Blast Fireball (7th level)