Dragon, Nidhogg

Gargantuan dragon, neutral evil

Armor Class 22 (natural armor)
Hit Points 367 (21d20 + 147)
Speed 40 ft., fly 80 ft., burrow 40 ft.

STR	DEX	CON	INT	WIS	CHA
27 (+8)	14 (+2)	25 (+7)	16 (+3)	15 (+2)	19 (+4)

Saving Throws Dexterity +10, Constitution +15, Wisdom +10, Charisma +12
Skills Nature +11, Perception +10, Stealth +10
Damage Immunities necrotic, poison
Condition Immunities charmed, exhaustion, frightened, paralyzed, poisoned
Senses blindsight 60 ft., darkvision 120 ft., passive Perception 20
Languages Common, Draconic
Challenge 25 (75,000 XP)

Special Traits

• Legendary Resistance (3/Day). If the nidhogg fails a saving throw, it can choose to succeed instead.
• Magic Resistance. The nidhogg has advantage on saving throws against spells and other magical effects.
• Magic Weapons. The nidhogg’s weapon attacks are magical.
• Siege Monster. The nidhogg deals double damage to objects, plants, and structures.

Actions

• Multiattack. The nidhogg can use its Frightful Presence. It then makes three attacks: one with its bite and two with its claws.
• Bite. Melee Weapon Attack: +16 to hit, reach 15 ft., one target. Hit: 19 (2d10 + 8) piercing damage plus 9 (2d8) necrotic damage. The target’s hit point maximum is reduced by an amount equal to the necrotic damage taken, and the nidhogg regains hit points equal to that amount. The reduction lasts until the target finishes a long rest. The target dies if this effect reduces its hit point maximum to 0.
• Claw. Melee Weapon Attack: +16 to hit, reach 10 ft., one target. Hit: 15 (2d6 + 8) slashing damage.
• Tail. Melee Weapon Attack: +16 to hit, reach 20 ft., one target. Hit: 17 (2d8 + 8) bludgeoning damage.
• Frightful Presence. Each creature of the nidhogg’s choice that is within 120 feet of the nidhogg and aware of it must succeed on a DC 18 Wisdom saving throw or become frightened for 1 minute. A creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success. If a creature’s saving throw is successful or the effect ends for it, the creature is immune to the nidhogg’s Frightful Presence for the next 24 hours.
• Swallow. The nidhogg makes one bite attack against a Large or smaller creature it is grappling. If the attack hits, the target takes the bite’s damage, the target is swallowed, and the grapple ends. While swallowed, the creature is blinded and restrained, it has total cover against attacks and other effects outside the nidhogg, and it takes 56 (16d6) necrotic damage at the start of each of the nidhogg’s turns. If the nidhogg takes 60 damage or more on a single turn from a creature inside it, the nidhogg must succeed on a DC 23 Constitution saving throw at the end of that turn or regurgitate all swallowed creatures, which fall prone in a space within 10 feet of the nidhogg. If the nidhogg dies, a swallowed creature is no longer restrained by it and can escape from the corpse by using 30 feet of movement, exiting prone.

Legendary Actions

The nidhogg 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 nidhogg regains spent legendary actions at the start of its turn.

• Detect. The nidhogg makes a Wisdom (Perception) check.
• Tail Attack. The nidhogg makes a tail attack.
• Chomp (Costs 2 Actions). The nidhogg makes one bite attack or uses its Swallow.

About

This skeletal dragon grips corpses in its claws, taking huge, slurping bites out of the meals.

Nidhogg dragons are ancient beings corrupted by horrible magics to destroy all that is natural. Their endless hunger is never satiated by the corpses they feast on; when they cannot find dead bodies, they resort to chewing on trees, destroying them at the root.

Dark Origins. No one is sure where nidhoggs come from or why they exist; one theory is that they will always exist, as long as there are eagles in the sky, there are worms in the ground, and so too the supernatural beings must destroy the old to allow for the new. Woe to Midgard should a nidhogg be free.