Actions

• Multiattack. The Nuckelavee makes 3 attacks: 1 with its horse, and 2 with its torso
• Horse: Poison Breath. The Nuckelavee exhales poisonous gas in a 30-foot cone. Each creature in that area must make a DC 15 Constitution saving throw, taking 35 (10d6) poison damage on a failed save, or half as much damage on a successful one. In addition on a failed save the creature is poisoned for the next hour.
• Horse: Kick. Melee Weapon Attack. +10 to hit, reach 5 ft., one target. Hit: 7 (2d8+8) bludgeoning damage.
• Torso: Whip. Melee Weapon Attack. +10 to hit, reach 10 ft., one target. Hit: 7 (2d4+8) slashing damage.

Legendary Actions

The Nuckelavee can take 3 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. The Nuckelavee regains spent legendary actions at the start of its turn.   Equine Glare (Costs 2 Actions). Cast the spell fear without using Spell Slots. You project a phantasmal image of a creature’s worst fears. Each creature in a 30-foot cone must succeed on a Wisdom saving throw or drop whatever it is holding and become frightened for the duration. While frightened by this spell, a creature must take the Dash action and move away from you by the safest available route on each of its turns, unless there is nowhere to move. If the creature ends its turn in a location where it doesn’t have line of sight to you, the creature can make a Wisdom saving throw. On a successful save, the spell ends for that creature.   Flailing Assault (Cost 1 Action). The Nuckelavee may make a Multiattack on a target.

Lair Actions

On initiative count 20 (losing initiative ties), the Nuckelavee can take a lair action to cause one of the following magical effects; the Nuckelavee can’t use the same effect two rounds in a row:   The Nuckelavee summons water form the depths of the sea near its lair to fill the area around its lair making it difficult for creatures to move. A creature can only move at half speed in difficult terrain— moving 1 foot in Difficult Terrain costs 2 feet of speed—so you can cover only half the normal distance in a minute, an hour, or a day. This lasts until initiative count 20 on the next round or until the Nuckelavee or the target creatures are no longer near the lair.   Tide pools of brackish water that the Nuckelavee can see within 120 feet of it surge outward in a grasping tide. Any creature on the ground within 20 feet of such a pool must succeed on a DC 15 Strength saving throw or be pulled up to 20 feet into the water and knocked prone.   From the salt and sand the Nuckelavee summons smaller versions of itself. The Nuckelavee summons 2d6 medium sized creatures with an AC of 10 and 1 HP. They share the same skills, ability scores, and actions as the original. They all take their actions on the same turn as they are summoned. They last until initiative count 20 on the next round, or until the Nuckelavee or the target creatures are no longer near its lair, or they are all destroyed.

The lair of a Nuckelavee isn't exactly clear in where its borders begin or end; typically it is found near areas that serve either as a crossing to the Feywild, Shadowfell, or both.

Regional Effects

It is also not clear whether the magical effects near or around the lair are caused by the crossings, or does the mere presence of its lair create these crossings. Regardless, the waters near the Nuckelavee's lair are typically brackish in nature with a strong stench of rotting flesh and lowtide always present. Fish and other watery creatures in the area are typically very sick or poisonous to consume even when they'd ordinarily be perfect for consumption. Plants in the area are much the same in being equally sick or poisonous to consume. No one has ever seen the "inside" of the Nuckelavee's lair, but its effects and lair actions extend to just along the perimeter and general area of the lair.

Suggested Environments

Coast, Swamp, Underdark, Shadowfell, Feywild