Huge fiend (demon), chaotic evil

Armor Class: 19 (natural armor)

Hit Points: 575 46d12+276

Speed: 50 ft , climb: 50 ft

STR

29 +9

DEX

16 +3

CON

23 +6

INT

15 +2

WIS

24 +7

CHA

15 +2

Saving Throws: Con +13

Skills: Intimidation +9, Perception +14

Damage Resistances: Cold, Fire, Lightning; Attacks made without advantage

Damage Immunities: Poison; Bludgeoning, Piercing, and Slashing from nonmagical attacks

Condition Immunities: Charmed, Exhaustion, Frightened, Poisoned

Senses: Truesight 120 ft.

Languages: all, telepathy 120 ft.

Challenge Rating: 24 ( 62,000 (75,000 in lair) XP)

Proficiency Bonus: +7

Actions

Multiattack. Yeenoghu makes three attacks, one of which may be his Bite.

Bite. Melee Weapon Attack: +16 to hit, reach 10 ft., one target. Hit: 20 (2d10 + 9) acid damage and the creature is grappled. While Yeenoghu has a creature grappled in this way, he can't bite another creature. While the creature is grappled, it automatically takes damage from Yeenoghu's bite on the start of each of his turns. The creature can use it action to attempt a Strength (Athletics) check or Dexterity (Acrobatics) contested by Yeenoghu's Strength (Athletics) check to end the grapple.

Flail. Melee Weapon Attack: +16, reach 15 ft., one creature. Hit: 22 (2d12 + 9) bludgeoning damage. If it's his turn, Yeenoghu can cause the target to suffer one of the following additional effects, each of which he can apply only once per turn:

• Decay. If the target is wearing nonmagical armor, it suffers a permanent and cumulative -1 to the AC it offers.
• Hunger. The target must succeed on a DC 17 Con saving throw or lose three unexpended hit dice. If the target cannot, it instead takes a level of exhaustion.
• Pain. The target takes an additional 13 (2d12) psychic damage.
• Terror. The target must succeed on a DC 17 Wisdom saving throw or be Frightened of Yeenoghu until the end of its next turn. A creature that fails its saving throw by 5 or more is instead Paralyzed until the end of its next turn.

Path of Ruin (Recharge 5-6). Yeenoghu moves up to his speed in a straight line. He can move thorugh the space of any creature smaller than Huge. Each creature whose space he moves through must succeed on a DC 24 Strength saving throw or take 3d12 bludgeoning damage and be knocked prone.

Bonus Actions

Rampage. When Yeenoghu reduces a creature to 0 hit points with a melee attack on its turn, Yeenoghu can take a bonus action to move up to half his speed and make a bite attack.

Reactions

Gorecall. As a reaction to being hit with a ranged attack, Yeenoghu forces the attacker to succeed on DC ## Strength saving throw or be pulled 20 ft toward him and knocked prone.

Viviphage Spawning (1/day). As a reaction to being reduced below 283 hit points, Yeenoghu creates four Fangs of Yeenoghu (MM14 p 163) within his body, which immediately chew their way out of his wounds and land prone in the nearest unoccupied spaces. Yeenoghu takes 25 (6d6+4) force damage from the horrid spawning.

Legendary Actions

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

Feral Pursuit. Up to thee of Yeenoghu's allies within 60 feet that can hear Yeenoghu may immediately use their reaction to move up to their speed toward a creature of Yeenoghu' choice without provoking attacks of opportunity.

Wake Bones. One friendly gnoll within 60 feett becomes suffused with negative energy, taking 14 (4d6) necrotic damage. If the the target dies in the next minute, its flesh sloughs off and it immediately rises as a Witherling.

Flesh Sacrifice (Costs 2 Actions). Yeenoghu makes a Bite attack. If the Bite attack hits, the target is not considered grappled. Yeenoghu regains hit points equal to the damage dealt.

Lair Actions

On initiative count 20 (losing initiative ties), Yeenoghu can take one of the following lair actions; he can't take the same lair action two rounds in a row:

Blood Feast. One creature within 30 ft that has fewer than half of its hit points must succeed on a DC 17 Constitution saving throw or be marked as prey. For the next minute, gnolls and hyenas may make use a bonus action to make a Bite attack against the creature. This effect ends early if the creature regains any hit points.

Iron Spike. Yeenoghu causes an iron spike—5 feet tall and 1 inch in diameter—to burst from the ground at a point he can see within 100 feet of him. Any creature in the space where the spike emerges must make a DC 24 Dexterity saving throw. On a failed save, the creature takes 27 (6d8) piercing damage and is restrained by being impaled on the spike. A creature can use an action to remove itself (or a creature it can reach) from the spike, ending the restrained condition.

Pack Rush. Each gnoll or hyena that Yeenoghu can see can use its reaction to move up to its speed.

Regional Effects

The region containing Yeenoghu's lair is warped by his magic, creating one or more of the following effects:

Savage Predators. Predatory beasts within 6 miles of the lair become unusually savage, killing far more than what they need for food. Carcasses of prey are left to rot in an unnatural display of wasteful slaughter.

Spiky Terrain. Within 1 mile of the lair, large iron spikes grow out of the ground and stone surfaces. Yeenoghu impales the bodies of the slain on these spikes.

Usual Tactics

Yeenoghu's allies never rush into combat ahead of him, because to do so is certain death. Yeenoghu opens with Path of Ruin and tries to hit as many creatures as possible. He uses his Butcherflail, focusing on a single target until it drops, biting and beginning to swallow it as a bonus action, and then moving on to the next on his following turn. Early in a fight, he uses Decay and Terror on the flail, then switches to Hunger and Pain after the toughest looking opponents are softened up.

If none of his enemies are flying, he used his Gorecall whenever he has the chance, but saves it for a flying enemy or other target that is trying to stay out of his reach.

Once a creature is marked by his Blood Feast, he uses Feral Pursuit and Pack Rush to get as many gnolls in range of that character as possible. He uses Wake Bones only on an already injured gnoll, unless all available targets are marked by his Blood Feast.