Fierna

Medium Fiend (Devil), Lawful Evil

AC: 20

Initiative: +7 (17)

HP: 367 (35d8 + 210)

Speed: 30 ft., fly 60 ft.

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

Saving Throws: Dex +15, Con +14, Wis +14, Cha +17

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

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

Immunities: cold; 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)

Fear Aura.

When a creature starts their turn within 120 feet of Fierna, 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.

Fierna regains 20 hit points at the start of her turn. If she takes radiant damage this trait doesn't function at the start of her next turn. Fierna dies only if she starts her turn with 0 hit points and is unable to regenerate.

Legendary Resistance (3/Day).

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

Magic Resistance.

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

Princess of Hellfire.

Fire conjured by Fierna becomes Hellfire. It ignores resistances and immunities to fire damage, deals double damage to creatures vulnerable to fire or necrotic damage, can't be extinguished through any means, and is capable of melting stone or igniting inflammable objects.

Actions

Multiattack.

Fierna makes three attacks using Flame Blade, Mote of Flame, or a combination of the two.

Flame Blade.

Melee Spell Attack: +20 to hit, reach 5 ft., one target. Hit: 23 (4d6 + 9) fire damage.

Mote of Flame.

Fierna targets a creature she can see within 90 feet of her. The target must make a DC 25 Dexterity saving throw, taking 22 (3d8 + 9) fire damage on a failed save, or half as much damage on a successful one.

Reactions

Wreath of Flames.

When hit by a melee attack and Fierna can see her attacker, she covers herself in Hellfire, and the attacker takes 13 (3d8) fire damage.

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.

Blade.

Fierna makes a Flame Blade attack.

Conjure Hellfire (Costs 2 Actions).

Fierna chooses a point she can see within 150 feet of her. All creatures in a 20-foot-radius sphere centered on that point must make a DC 25 Dexterity saving throw, taking 28 (8d6) fire damage on a failed save, or half as much damage on a successful one.

Call Underling (Costs 3 Actions).

Fierna summons an allied spined devil in an unoccupied space that she can see.

Lair Actions

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

  • Fiery Reversal.

    Fierna exchanges places with a creature she can see within 30 feet of her. Both her old location and her new location erupt into flames that persist for 1 minute. Anyone entering either flame must succeed on a DC 21 Constitution saving throw or take 28 (8d6) fire 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 Fierna's lair is corrupted by her 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 Fierna dies, the effects fade over the course of 1d10 days.

Find this creature in the encounter builder

Fierna

Source: Chains of Asmodeus, p. 225 - Licenses and attribution