D&D 5E Epic Monsters: Jörmungandr

Epic Monsters is spanning the world today, stretching all the way to the Norse epics for one last post in this little mini-series of builds to consider that serpent to end all serpents Jörmungandr!

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There are a few myths central to the world-spanning Jörmungandr. One of the offspring of Loki and Angrboða (alongside its siblings Fenrir and Hel), it was first tied to a pine tree but proved feisty and spat venom at Odin. The Allgod then tossed it out into the oceans around Midgard where it grew and grew until it encircled the entire world. After that there are three very prevalent legends: Thor lifting it thinking it was a very big cat and nearly breaking the boundaries of existence by almost getting too much of it off the ground, when Thor caught it on a fishing line that Hymir fearfully cuts in twain to prevent Ragnarök from coming too early, and finally that when the apocalypse comes that the two will slay each other.

Design Notes: There were a few things to keep in mind while building Jörmungandr. First of all Thor has to be able to kill it. Granted he dies afterward and his dad can probably spare a spell or two for him to make it a touch easier, but it has to be killable by the man with Mjölnir. Then there’s representing the enormity bit so a proverbial page has been taken from the World Turtle’s book which brings us to the action economy at work. That discussion inevitably starts pouring love on Legendary Actions but between the occasional earthquake, the delayed hit with its tail, and the secondary effect of its poisonous bite there’s enough tracking going on with Jörmungandr already so this version is without. Let’s look at the numbers! The DMG landed on 23.16667 and the Blog of Holding smack dab on 23. It’s unlikely that the Odinson will win in a true one-on-one fight with the World Serpent—he’ll have much better chances battling alongside some adventurers ☜(゚ヮ゚☜)—but it’s not outside the realm of possibility with its hit points and him nailing with a fair number of smited critical hits. Those sorts of odds are, after all, part and parcel with world ending myths.


Gargantuan monstrosity, chaotic evil
Armor Class 17 (natural armor)
Hit Points 410 (20d20+200)
Speed 60 ft., climb 60 ft., swim 200 ft.
27 (+8)​
13 (+1)​
30 (+10)​
3 (–4)​
20 (+5)​
23 (+6)​
Saving Throws Int +3
Skills Athletics +15
Damage Resistances cold, fire; bludgeoning, piercing, and slashing
Damage Immunities acid, poison; bludgeoning, piercing, and slashing from nonmagical weapons
Condition Immunities blinded, charmed, deafened, exhaustion, frightened, paralyzed, petrified, poisoned, prone, stunned
Senses darkvision 300 ft., truesight 120 ft., passive Perception 15
Challenge 23 (50,000 XP)

Amphibious. Jörmungandr can breathe air and water.

Damage Threshold. Jörmungandr does not take damage from an attack, spell, or other effect that deals 10 points or less of bludgeoning, piercing, or slashing damage (calculated after resistances).

Freedom of Movement. Jörmungandr ignores difficult terrain, and magical effects can't reduce its speed or cause it to be restrained. It can spend 5 feet of movement to escape from nonmagical restraints or being grappled.

Legendary Resistance (3/Day). If Jörmungandr fails a saving throw, it can choose to succeed instead.

Magic Resistance. Jörmungandr has advantage on saving throws made against spells and other magical effects.

Magic Weapons. Jörmungandr’s weapon attacks are magical.

Ponderous Tail. Whenever Jörmungandr makes a Colossal Tail attack, its attack does not strike until the end of its next turn. If the target of its attack has moved out of the area Jörmungandr misses the target but may hit other creatures or objects still in the area.

Regeneration. Jörmungandr regains 10 hit points at the start of its turn. If Jörmungandr takes radiant damage, this trait doesn’t function at the start of its next turn. Jörmungandr dies only if it starts its turn with 0 hit points and doesn’t regenerate.

Seamaster. At the start of any turn that Jörmungandr has pulled at least 200 feet or more of its body out of the water, its absence sends the sea tumbling. Creatures within 50 feet of the part of Jörmungandr’s body that is still submerged must make a DC 23 Strength saving throw or be knocked prone and pushed 50 feet away from it.
When Jörmungandr starts its turn with less than 200 feet of its body out of the water, creatures within 50 feet of it must make a DC 23 Strength (Athletics) check to move in the water. Any creature that has a swim speed makes this check with advantage.

Siege Monster. Jörmungandr deals double damage to objects and structures.

World Tremors (Recharge 6). Jörmungandr can use a bonus action to innately cast earthquake (DC 21) without the need for material components, somatic components, or concentration.

Multiattack. Jörmungandr attacks twice: twice with its black venom, or once with its bite, and once with either colossal tail or constrict.

Bite. Melee Weapon Attack: +15 to hit, reach 30 ft., one target. Hit: 44 (6d10+11) piercing damage plus 27 (6d8) acid damage. In addition, at the end of its next turn the creature makes a DC 23 Constitution saving throw or it takes 27 (6d8) poison damage.

Colossal Tail. Melee Weapon Attack: +15 to hit, reach 120 ft., multiple targets more than 20 feet away from Jörmungandr (120-foot cone centered on one target; roll separately for each creature and object in the area). Hit: 37 (4d12+11) bludgeoning damage and the target makes a DC 23 Strength saving throw or is knocked prone.

Constrict. Melee Weapon Attack: +15 to hit, reach 20 ft., one creature. Hit: 38 (6d8+11) bludgeoning damage, and the target is grappled (escape DC 23). Until this grapple ends, the creature is restrained, and Jörmungandr can't constrict another target.

Black Venom. Ranged Weapon Attack: +8 to hit, range 50/100 ft., multiple targets (10-foot square; roll separately for each creature and object in the area). Hit: 27 (6d8) acid damage. In addition, at the end of its next turn the creature makes a DC 23 Constitution saving throw or it takes 27 (6d8) poison damage.
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Mike Myler

Mike Myler

There's good logic to that but the tracking involved with the delayed poison effect on its bite (which is a thing we want to maintain the most popular mythological story about Big J here) makes me very hesitant to inflict it upon more than one creature a round. That sounds like a GM-ing headache!
It would also mean a bump of at least 1-2 CR because the more creatures being targeted by the attack the more attack rolls it makes, and the more attack rolls it makes the higher the likelihood of a critical hit happening—which by this point in the damage dice means ~84 extra damage (or more, depending on how big the bite's area is and how many additional 'hits' it can net with that). When we get to "super kaiju shark" we'll dig into some area bites though for sure.
Omegaladon (y)

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