Sedna
Sedna — The Encounter
Mother of the Sea, Mistress of the Drowned Deep · a boss your table can run with almost no prep. SRD 5.1-compatible.
Who Is Sedna
Among the people of the ice, no spirit is feared and beseeched as Sedna, who dwells at the bottom of the cold sea and holds dominion over every creature that swims within it. The grimoires of the far north tell that she was once a mortal maiden cast from her father's boat into the freezing water; when she clung to the gunwale, her fingers were severed joint by joint, and from those falling pieces were born the first seals, walruses, and whales. Sunk to the seabed, she became mistress of the drowned, withholding the hunt's bounty from any who break the old taboos. Shamans must descend in trance to comb the tangles from her hair, for her grief becomes storms and her anger becomes famine. To wrong her is to be dragged beneath the floes; to honor her is to be fed through the long dark. She is neither cruel nor kind, only as constant and unforgiving as the sea itself.
Run Sedna in Sixty Seconds
- She is a fight in three dimensions — give her real water on the map. Her swim speed (90 ft.) and Undertow let her drag prey into the deep where they fight at disadvantage and she does not.
- Open with the Harpoon pull, not Drowning Surge. Hooking a backline caster and yanking them 15 ft. into melee breaks the party formation immediately and sets up everything else.
- Kill-priority is whoever hit her last — Tide-Sworn Vengeance gives her advantage against them, and Severed Hands punishes melee retaliation with cold damage plus temp HP, so she heals back into the fight.
- When bloodied, go evasive. Recharge Drowning Surge to prone the cluster, then Cold Current away into open water; let her temp HP and resistances stall while legendary actions chip the backline.
- Three ways to run her: a vengeful coastal demigod (solo, full legendary), the Mother of the Deep commanding Aklut and seal-spirits (boss + adds), or a wrathful storm-spirit in a shrine raid where players must appease rather than kill her.
Sedna
Large celestial, neutral
CR 11 · 7,200 XP · GUIDELINEAmphibious. Sedna can breathe air and water, and her movement is never hindered by difficult terrain made of water, ice, or snow.
Severed Hands of the Deep. Signature. Sedna's fingers were once struck away and became the first seals and whales. Each turn, when a creature within 30 ft. of her hits her with an attack, one of these spirit-beasts surges from the water: the attacker takes 7 (2d6) cold damage and Sedna gains 5 temporary hit points. This can trigger only once per turn.
Tide-Sworn Vengeance. Sedna has advantage on attack rolls against any creature that has dealt damage to her since her last turn.
Actions
Multiattack. Sedna makes two Harpoon attacks, or one Harpoon attack and one use of Drowning Surge (if available).
Harpoon. Melee or Ranged Weapon Attack: +9 to hit, reach 10 ft. or range 30/120 ft., one target. Hit: 19 (3d8 + 5) piercing damage plus 9 (2d8) cold damage. On a hit against a Large or smaller creature, Sedna can pull the target up to 15 ft. toward her.
Drowning Surge (Recharge 5-6). Sedna calls a crushing wave in a 30-foot cone. Each creature in the area must make a DC 17 Constitution saving throw, taking 36 (8d8) cold damage and being knocked prone on a failed save, or half as much damage and not prone on a success. Water-filled spaces in the area remain difficult terrain until the end of Sedna's next turn.
Bonus Actions & Reactions
Undertow (Reaction). When a creature Sedna can see within 30 ft. starts its turn, she can pull it up to 10 ft. toward the nearest body of water or open space; if this moves it into a hazard or off a ledge, it must succeed on a DC 17 Strength saving throw or be dragged in.
Legendary Actions (3/Round)
Harpoon Cast. Sedna makes one Harpoon attack.
Cold Current (Costs 1 Action). Sedna moves up to her swim speed without provoking opportunity attacks. Each creature she passes within 5 ft. of takes 5 (1d10) cold damage.
Wrath of the Deep (Costs 2 Actions). One creature Sedna can see within 60 ft. must succeed on a DC 17 Wisdom saving throw or be restrained by clutching currents until the end of its next turn, taking 11 (2d10) cold damage at the start of each of its turns while restrained.
Carved mid-rise from a towering breaker of translucent ocean, Sedna grips her long bone harpoon while her hair streams like kelp in the storm-surge, fur and sealskin lashed to a body that is half-woman, half-tide.
Sedna, Bound
Companion · acts on your initiative
Bound · GUIDELINEOrca's Wake (signature). Sedna, the spirit-orca of the floes, ignores difficult terrain in water and snow and has advantage on Stealth checks while submerged.
Actions
Rending Bite. Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 17 (3d8 + 4) piercing damage, and a Large or smaller target is grappled (escape DC 15).
Reactions
Breach. When a creature within 10 ft. of Sedna hits Sedna, Sedna surges from the water and the attacker must succeed on a DC 15 Strength save or be knocked prone.
The transforming wolf-orca of Inuit tale, Sedna runs the ice as a wolf and hunts the depths as a killer whale, ever at the Mother's side.
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 with a thrown Harpoon to yank your party's striker into melee and isolate them. If the group clusters near water, hold Drowning Surge for the line; kill-priority is anyone who dealt her damage last round, since Tide-Sworn Vengeance gives advantage. At this scale run her as a frightening miniboss in a coastal shrine, not a true deity.
Lead by hooking the squishiest caster with Harpoon and dragging them 15 ft. into the surf. When clustered, Drowning Surge prones the front line so melee allies pile on. Pair her with Aklut or a pack of frost-touched seals so she can reposition with Undertow while the beasts hold the line.
Open by harpooning the strongest single-target damage dealer and pulling them away from healers. Spend legendary actions on Harpoon Cast and Wrath of the Deep to restrain backline casters before they unload. When bloodied, recharge Drowning Surge becomes the priority — cone the cluster, prone them, then use Cold Current to escape into deep water and let Severed Hands punish every retaliation.
Put Sedna 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 Sedna?
Her home tier is Tier 3 (levels 11-15), built around CR 11 (7,200 XP): AC 17, 184 HP, +9 to hit, save DC 17. Because she has legendary actions she plays as a solo centerpiece and her sheet sits one band down from a multi-monster CR 11. Tier 1 and Tier 2 versions are provided for lower tables — same traits, smaller numbers.
Can Sedna be a companion or ally?
As a sea goddess she is far too vast to be a follower, but parties who honor the old taboos can earn her favor: she may calm a storm, restore a drowning ally, or send Aklut to fight alongside them for a single scene. Her companion Aklut (the wolf-orca spirit) makes an excellent allied beast at the table.
Does Sedna need water to be dangerous?
No, but she shines with it. On dry land she is still a hard-hitting harpoon striker with cold damage and legendary actions, but a map featuring open water, ice floes, or surf lets her swim speed, Undertow, and Drowning Surge turn the battlefield into her domain. Give her at least some water for the intended experience.
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
Played Sedna at your table? Log in with your Obsidian Tavern account to leave a balance note, a war story, or a file issue — the sharpest reports get the block revised.
Log in to comment