Belial

Medium Fiend (Devil), Lawful Evil

AC: 21

Initiative: +3 (13)

HP: 420 (40d8 + 240)

Speed: 30 ft., fly 60 ft.

STR: 25 (+7)
DEX: 17 (+3)
CON: 22 (+6)
INT: 22 (+6)
WIS: 22 (+6)
CHA: 29 (+9)

Saving Throws: Str +15, Dex +11, Con +14, Wis +14

Skills: Athletics +15, Deception +25, Insight +14, Intimidation +17, Perception +14, Persuasion +25

Resistances: cold; bludgeoning, piercing, slashing from nonmagical attacks that aren't silvered

Immunities: fire; poison

Condition Immunities: charmed; poisoned

Senses: darkvision 120 ft., Passive Perception 24

Languages: Celestial, Common, Draconic, Infernal, telepathy 120 ft.

CR: 25 (XP 75,000; PB +8)

Deep Wounds.

All damage dealt by Belial can only be restored through magical means.

Devil's Sight.

Magical darkness doesn't impede Belial's darkvision.

Fear Aura.

When a creature starts their turn within 120 feet of Belial, they must succeed on a DC 22 Wisdom saving throw or have the frightened condition until they leave the aura. A creature that succeeds on the saving throw is immune to this effect for 1 hour.

Fiendish Regeneration.

Belial regains 20 hit points at the start of his turn. If he takes radiant damage this trait doesn't function at the start of his next turn. Belial dies only if he starts his turn with 0 hit points and doesn't regenerate.

Legendary Resistance (3/Day).

If Belial fails a saving throw, he can choose to succeed instead.

Magic Resistance.

Belial has advantage on saving throws against spells and other magical effects.

Actions

Multiattack.

Belial makes three attacks using his Ranseur of Torture.

Ranseur of Torture.

Melee Weapon Attack: +18 to hit, reach 10 ft., one target. Hit: 21 (2d10 + 10) piercing damage plus 5 (1d10) necrotic damage, and the target must make a DC 23 Constitution saving throw. On a failed save, the target's movement speed is reduced by 5 feet until the end of their next turn. This penalty can stack.

Walls of Phlegethos.

Belial creates a wall of fire on a solid surface within 120 feet of him. The wall is 20 feet high and 1 foot thick, and Belial can make the wall up to 60 feet long or create a ringed wall up to 20 feet in diameter. The wall is opaque and lasts until Belial dismisses it. When the wall appears, each creature within its area must make a DC 25 Dexterity saving throw, taking 36 (8d8) fire damage on a failed save, or half as much damage on a successful one. A creature that ends its turn inside the wall, or within 5 feet of it, must repeat the save.

Symbol of Insanity (Recharge 4-6).

Belial draws a magic symbol at a point he can see within 120 feet of him. All creatures within a 20-foot-radius sphere centered on the symbol must make a DC 25 Intelligence saving throw. Targets take 45 (10d8) psychic damage on a failed save, or half as much damage on a successful one. Creatures that fail the save immediately use their reaction to make a melee attack against a random creature within their reach, then move their full movement in a random direction.

Reactions

Pleasure in Pain.

As a reaction to taking damage, Belial immediately regenerates half the damage he took.

Legendary Actions

Legendary Action Uses: 3. Immediately after another creature's turn, this creature can expend a use to take one of the following actions; it regains all expended uses at the start of each of its turns.

Ranseur.

Belial makes a Ranseur of Torture attack.

Eruption (Costs 2 Actions).

Belial causes molten stone to erupt from a point he can see within 90 feet of him. All creatures within a 20-foot-radius sphere centered on that point must make a DC 23 Dexterity saving throw. Targets take 28 (8d6) fire damage on a failed save, or half as much damage on a successful one.

Call Underling (Costs 3 Actions).

Belial summons an allied horned devil in an unoccupied space that he can see.

Lair Actions

On initiative count 20 (losing initiative ties), Belial can take one lair action to cause the following effect or one from the archdevil lair action list (page 214); he can't take the same lair action two rounds in a row:

Slow Torture.
Every creature within 100 feet whose movement is currently reduced because of the Ranseur of Torture, takes 11 (2d10) fire damage and 11 (2d10) piercing damage.

Attack.
The archdevil uses one of their available melee or ranged attacks against a single foe.
Cast a Spell.
The archdevil uses their Spellcasting feature to cast an available spell. If the spell normally requires concentration, it lasts for the full duration instead.
Deceitful Whispers.
The archdevil whispers to a creature they can see within 30 feet. The target must make a DC 22 Wisdom saving throw. On a failed save, the target has the charmed condition until the start of their next turn and must use their reaction immediately to make an attack against one of the archdevil's enemies, chosen by the archdevil.
Fiendish Fortitude.
The archdevil recharges one of their expended abilities.
Frenzy.
The archdevil casts Haste on themself. The effect ends at initiative count 20 of the next round.
Summon Underlings.
The archdevil summons allied devils. The devils summoned depends on the archdevil using this feature. The summoned devils appear in unoccupied spaces which the archdevil can see. The Summoned Underlings table shows which devils each archdevil can summon.
Teleport.
The archdevil teleports themself to an area they can see within 120 feet.
Trap.
The archdevil casts the Hold Monster spell.

Regional Effects

The region containing Belial's lair is corrupted by his presence, which creates the following effect:

Smoke-cloud.
A vast fog rises 3 feet above ground within 1 mile of the lair, completely obscuring the ground. Any creature having the prone condition at the start of their turn must succeed on a DC 22 Constitution saving throw or take 7 (2d12) necrotic damage from choking on the noxious fumes.

If Belial dies, the effects fade over the course of 1d10 days.

Find this creature in the encounter builder

Source: Chains of Asmodeus, p. 221 - Licenses and attribution