Huge undead, chaotic evil
- Armor Class 16 (natural armor)
- Hit Points 420 (40d10 + 160)
- Speed 50 ft., swim 50ft.
- Saving Throws Str +12, Con +10, Int +10
- Skills Athletics +12, Perception +7
- Damage Resistances cold, necrotic
- Damage Immunities Bludgeoning, Piercing & Slashing damage from nonmagical weapons
- Senses Passive Perception 17
- Challenge 23 (50,000 XP)
- Dragged to the Grave. The Nuckelavee does not have its speed reduced while grappling a creature. If the Nuckelavee moves while it is grappling a creature, the grappled creature suffers 1 point of bludgeoning damage for every 5 feet the Nuckelavee moves.
- Legendary Resistances (3/day). If the Nuckelavee fails a saving throw, it can choose to succeed it instead.
- Omen of Death. The Nuckelavee does not breathe and it does not require sleep, food or water to survive. All crops within 500 feet of the Nuckelavee wither and die. Plant creatures starting their turn within 500 feet of the Nuckelavee suffer 4d10 necrotic damage.
- Freshwater Sensitivity. When the Nuckelavee is submerged in or has at least 10 gallons of fresh water it loses its ability to use Legendary Actions for 1 minute.
- Multiattack. The Nuckelavee can use it’s Polluting Breath then make four attacks, one with its hooves, one with its bite, one with its claw and one with its spear.
- Hoof. Melee Weapon Attack: +12 to hit, reach 10 ft., one target. Hit: 30 (6d6 + 6) bludgeoning damage. On a hit the target must make a DC 18 Strength saving throw or be knocked prone.
- Bite. Melee Weapon Attack: +12 to hit, reach 10 ft., one target. Hit: 30 (6d6 + 6) piercing damage. On a hit the creature must make a DC 18 Constitution saving throw or gain the disease Grim Wasting. A creature affected by Grim Wasting cannot recover hit points using hit or when taking a long rest.
- Claw. Melee Weapon Attack: +12 to hit, reach 10 ft., one target. Hit: 30 (6d6 + 6) piercing damage. A creature hit by this attack is grappled by the Nuckelavee. The Nuckelavee cannot use this attack against a different creature until it ends the grapple on the currently grappled creature.
- Spear. Melee Weapon Attack: +12 to hit, reach 10 ft., one target. Hit: 39 (6d8 + 6) piercing damage.
- Polluting Breath. The Nuckelavee spews a cloud of toxic miasma in a 30 foot radius around it. Any creature in this area must make a DC 18 Constitution saving throw or suffer 33 (6d8) poison damage and become poisoned. A creature that succeeds takes half as much damage and is not poisoned.
The Nuckelavee can take 3 Legendary Actions, choosing from the options below. Only one legendary action can be used at a time, and only at the end of another creature's turn. Spent legendary Actions are regained at the start of each turn.
- Drag to Death. The Nuckelavee makes one Claw Attack and moves 20 feet without provoking attacks of opportunity.
- Toxic Bite. The Nuckelavee makes one Bite Attack.
- Grave Whinny (Costs 2 Actions). The Nuckelavee emits a terrible screech that grips the soul with fear. All creatures within 120 feet that can hear the Nuckelavee must make a DC 18 Wisdom saving throw or become frightened of the Nuckelavee. Creatures frightened this way are paralyzed. Creatures can repeat this saving throw at the end of each of their turns to end the frightened condition. A creature that succeeds on the saving throw is immune to the Grave Whinny for 24 hours.