Gargantuan fiend, neutral evil
- Armor Class 20 (natural armor)
- Hit Points 364 (11d20+66)
- Speed 50 ft., fly 60ft.
- Saving Throws Str +14, Con +12, Wis +9, Cha +12
- Skills Intimidation +12, Perception +9
- Damage Resistances poison, lightning; bludgeoning, piercing and slashing from nonmagical attacks
- Damage Immunities fire
- Condition Immunities poisoned, frightened
- Senses truesight 120 ft., passive Perception 13
- Languages Abyssal, Telepathy 120 ft.
- Challenge 20 (25,000 XP)
- Fire Aura. At the start of each of the balrog's turns, each creature within 10 feet of it takes 14 (4d6) fire damage, and flammable objects in the aura that aren't being worn or carried ignite. A creature that touches the balor or hits it with a melee attack while within 5 feet of it takes 14 (4d6) fire damage.
- Innate Spellcasting. The balrog's spellcasting ability is Charisma (spell save DC 20). The balrog can innately cast the following spells, requiring no material components:
At will: fireball, smoke screen
3/day each: hold creature, wall of fire
1/day: incendiary cloud
- Magic Resistance. The balrog has advantage on saving throws against spells and other magical effects.
- Magic Weapons. The balrog's weapon attacks are magical.
- Multiattack. The balrog makes three attacks: one with its whip, one with its sword, and one with its bite
- Bite. Melee Weapon Attack: +14 to hit, reach 10ft., one target. Hit: 22(4d6+8) piercing damage.
- Balrog's Blade. Melee Weapon Attack: +14 to hit, reach 10ft., one target. Hit 26 (4d8 + 8) slashing damage plus 21 (6d6) fire damage.
- Flame Whip. +14 to hit, reach 40ft., one target. Hit: 19(3d6+8) slashing damage plus 14 (4d6) fire damage, and the target must succeed on a DC 20 Strength saving throw or be pulled up to 25 feet toward the balor.