Corrupted Jormungandr
Corrupted Jormungandr — The Encounter
The World-Girdling Serpent, Venom of the Encircling Sea · a boss your table can run with almost no prep. SRD 5.1-compatible.
Who Is Corrupted Jormungandr
Of the great serpent that girdles the world, the eddas speak in hushed dread: cast into the encircling sea while still small, it grew until its body ringed all lands and its jaws closed upon its own tail. Sailors name it the Venom-Wyrm, for the waters it swims through curdle and the fish float belly-up in its wake. Where it surfaces, storms follow; where it dives, whirlpools swallow ships whole. The corruption upon its scales is no disease but its very nature — a creature born to be the world's ending, biding in the black trenches until the day the sea itself rises. Skalds warn that to strike it is to wake it, and to wake it fully is to call down the drowning of all things. Those who have glimpsed its coil and lived speak only of a green light beneath the waves, vast and patient, and the smell of poison on the wind.
Run Corrupted Jormungandr in Sixty Seconds
- Hold the aura. Venom Aura ticks 2d6 poison at the START of the serpent's turn to everyone within 10 ft. — tell melee players up front so they choose to crowd it knowingly, not feel cheated.
- Open with a grapple. Lead Constrict on the front-liner or, better, the caster: grappled AND restrained, then Drag Under hauls them toward water for the drowning save.
- Kill-priority. The serpent fixates on whoever can undo a grapple at range — dispel, teleport, freedom of movement. Drag that PC under first.
- When bloodied, stop trading blows: dive each round with Drag Under, surface to Spew Brine, and use Tightening Coil reactions to bleed grappled PCs while they flail.
- Three ways to run it: (1) solo boss at T3 with full legendary actions; (2) T2 muscle paired with a sea-witch or coastal cult; (3) T1 flooded-shrine centerpiece flanked by Brine-Spawn add-ons.
Corrupted Jormungandr
Gargantuan monstrosity, chaotic evil
CR 11 · 7,200 XP · GUIDELINEVenom Aura. The serpent exhales a corrupting haze. At the start of each of the serpent's turns, every creature within 10 feet of it must succeed on a DC 16 Constitution saving throw or take 7 (2d6) poison damage. This is the signature dread of the World Serpent: it poisons the very air it coils through.
Constrictor. A creature grappled by the serpent (escape DC 17) is also restrained, and the serpent can move at full speed while dragging it. The serpent can grapple two creatures at once.
Actions
Multiattack. The serpent makes one Bite attack and one Tail Slam attack. It can replace the Bite with a Constrict against a creature it has not yet grappled.
Bite. Melee Weapon Attack: +9 to hit, reach 10 ft., one target. Hit: 18 (3d8 + 5) piercing damage plus 10 (3d6) poison damage.
Tail Slam. Melee Weapon Attack: +9 to hit, reach 15 ft., one target. Hit: 17 (2d10 + 6) bludgeoning damage, and the target must succeed on a DC 16 Strength saving throw or be knocked prone.
Constrict. Melee Weapon Attack: +9 to hit, reach 10 ft., one Large or smaller creature. Hit: 15 (2d8 + 6) bludgeoning damage, and the target is grappled (escape DC 17) and restrained per Constrictor.
Bonus Actions & Reactions
Tightening Coil. When a creature the serpent is grappling tries to escape or attacks the serpent, the serpent can squeeze: that creature takes 9 (2d8) bludgeoning damage.
Legendary Actions (3/Round)
Lash. The serpent makes one Tail Slam attack.
Drag Under (Costs 2 Actions). The serpent moves up to its swim speed without provoking opportunity attacks, dragging any creature it has grappled with it. If it ends this move in water, each dragged creature must succeed on a DC 16 Strength saving throw or begin drowning.
Spew Brine (Costs 2 Actions). The serpent vomits a 20-foot cone of corrupted seawater. Each creature in the cone makes a DC 16 Constitution saving throw, taking 14 (4d6) poison damage on a failure, or half as much on a success.
A gargantuan ocean serpent rears from its own coils, green-gold scales slick with brine and rot, its frilled draconic head splitting into a venom-dripping maw. This is the World Serpent of the deep, so vast it is said to encircle the lands and bite its own tail.
Corrupted Jormungandr, Bound
Companion · acts on your initiative
Bound · GUIDELINEWake of Rot (signature). Difficult terrain caused by water or muck does not slow the brine-spawn, and it has advantage on saving throws against being poisoned.
Actions
Fanged Coil. Melee Weapon Attack: +7 to hit, reach 10 ft., one target. Hit: 14 (2d8 + 5) piercing damage plus 7 (2d6) poison damage.
Reactions
Whipback. When a creature within 5 feet hits the brine-spawn, it can lash its tail, dealing 7 (2d6) bludgeoning damage to that creature.
A lesser serpent calved from the World-Wyrm's molt, smaller but no less venomous, slithering ahead to herald the great coil's rise.
Guideline numbers — formula-tuned and read from the miniature's design, not yet table-proven. Tell us how it ran in the comments.
How It Fights — by Tier
Same creature, scaled threat. The traits never change; only the numbers move.
Open by surfacing into the cluster and using Venom Aura to grind down anyone who crowds it; melee parties WILL crowd it. Constrict the squishiest caster first and drag them to the back. At this tier run it as a flooded-cave centerpiece with a couple of Brine-Spawn add-ons rather than a true boss.
Lead with Constrict on the front-liner, then bite the healer — grappled, restrained, and dragged toward water. Use Venom Aura to punish melee stacking; force them to spread out. Pairs well below its native tier as the muscle behind a sea-witch or coastal cultist.
Run it solo: open with Spew Brine into the cluster, then Constrict + Bite the lowest-AC target. Kill-priority is anyone who can break a grapple from range (counterspell, teleport, dispel) — Drag Under removes them into drowning water. When bloodied, lean on legendary Lash + Tightening Coil to keep two PCs pinned while it dives between turns.
Put Corrupted Jormungandr on the table
Download the presupported STL and run the fight tonight — the model, and the encounter that comes with it.
Get the STL on MyMiniFactory →Clay Cyanide Companion Rules v1
How a bound creature acts
- A companion acts on its owner's initiative, immediately after the owner.
- It uses the Companion block above — roughly ×0.6 HP and damage, no recharge abilities, and at most one reaction trait.
- It moves freely; it takes its Action only while its owner is conscious.
- At 0 HP a companion is broken, not dead — restored on a long rest unless your table rules otherwise.
Original Clay Cyanide material © Clay Cyanide LLC — explicitly not the non-SRD official sidekick rules.
Questions, Asked at the Table
What CR is Corrupted Jormungandr?
Its native sheet is CR 11 (7,200 XP), a Tier 3 (levels 11-15) centerpiece. As a genuine solo boss it carries legendary actions, so it plays up a band — treat it as a full-party threat. Scaled stat lines for Tier 1 and Tier 2 are provided if you want it as a lesser flooded-cave horror.
Can Corrupted Jormungandr be a companion or ally?
The World Serpent itself is far too vast and malign to bind, but its molt-calf, the Brine-Spawn, can be loosed alongside a party or sea-cult — a poison-fanged coil (AC 14, 124 HP) that ignores watery terrain and lashes back at attackers.
How do I keep the grapple-and-drown loop from feeling unfair?
Telegraph it. Describe the coils tightening and the water rising before the first Drag Under, and make sure at least one drowning save and one escape DC check happen in the open. Give grappled PCs a clear out — an ally can attack the coil, and breaking line to water buys a turn. The serpent is meant to feel inevitable, not cheap.
Tell Us How It Ran
This work includes material taken from the System Reference Document 5.1 ("SRD 5.1") by Wizards of the Coast LLC and available at dnd.wizards.com/resources/systems-reference-document. The SRD 5.1 is licensed under the Creative Commons Attribution 4.0 International License available at creativecommons.org/licenses/by/4.0/legalcode.
Clay Cyanide Miniatures is not affiliated with, endorsed, sponsored, or specifically approved by Wizards of the Coast LLC. This content is compatible with the fifth edition of the world's most popular fantasy roleplaying game. Companion rules, lore, names, and original mechanics © Clay Cyanide LLC.
Technical Specifications
32mm, 75mm
STL, Pre-supported STL
Standard or ABS-like resin, 0.05mm layer height
Yes — ready to print, optimized supports included
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