Legendary Resistance (3/Day). If Yeenoghu fails a saving throw, he can choose to succeed instead.
Magic Resistance. Yeenoghu has advantage on saving throws against spells and other magical effects.
Multiattack. Yeenoghu makes three Flail attacks or two bite attacks and one spellcast.
Flail. Melee Weapon Attack: +17 to hit, reach 15 ft., one target. Hit: 22 (2d12 + 10) force 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:
Confusion. The target must succeed on a DC 22 Wisdom saving throw or be affected by the confusion spell until the start of Yeenoghu’s next turn.
Pinned. The target takes an extra 7 (1d12) force damage and is pinned to a flail spike. At start of turn, the target must succeed on a DC16 strength save or remain pinned to the flail and take (1d12) force damage every time the flail hits a target. May attack Yeenoghu with disandvantage.
Which flail pinned to: #1 #2 #3
Paralysis. The target must succeed on a DC 18 Constitution saving throw or be paralyzed until the start of Yeenoghu’s next turn.
Bite. Melee Weapon Attack: +17 to hit, reach 10 ft., one target. Hit: 20 (2d10 + 10) acid damage.
Spellcasting. Yeenoghu casts one of the following spells, requiring no material components and using Charisma as the spellcasting ability (spell save DC 22):
At will: detect magic
3/day each: dispel magic , fear , invisibility
1/day: teleport
Rampage. When Yeenoghu reduces a creature to 0 hit points with a melee attack, he moves up to half his speed and makes one Bite attack.
Yeenoghu can take 4 legendary actions, choosing from the options below. Only one legendary action option can be used at a time and only at the end of another creature’s turn. One turn after Yeenoghu has spent all his legendary actions he regains them.
Charge. Yeenoghu moves up to his speed and make a Bite attack.
Swat Away. Yeenoghu makes one swiping Backhand attack: +17 to hit, reach 10 ft., one target. Hit: 20 (2d10 + 10) bludgeoning damage. If the attack hits, the target must succeed on a DC 27 Strength saving throw or be thrown up to 30 feet in a straight line away from Yeenoghu. If the saving throw fails by 5 or more, the target is also knocked prone. If an obstacle is hit (1d8 +10) bludgeoning to all involved.
Savage (Costs 2 Actions). Yeenoghu makes a separate Bite attack against each creature within 10 feet of him.