Koschei the Deathless
Koschei the Deathless — The Encounter
The undying sorcerer whose death sleeps inside a needle · a boss your table can run with almost no prep. SRD 5.1-compatible.
Who Is Koschei the Deathless
In the old tellings of the eastern marsh-kingdoms, Koschei the Deathless bartered away his own dying so that no sword, age, nor poison could claim him. He drew his soul out of his breast as a smith draws a splinter and hid it: thrust into a needle, and the needle into an egg, and the egg into a duck, and the duck into a hare, and the hare locked within an iron-bound chest beneath the roots of an oak on a nameless island. So long as that needle lies unbroken, he walks the world undefeated, raising the war-dead as his boyars and demanding tribute in maidens and in fear. He is no brute despite his horns; he is a patient, gloating sorcerer who lets heroes hew at him only to laugh as their wounds knit. The riddle of his life is the only weapon that frightens him, and he guards its keeping with a cunning equal to his cruelty.
Run Koschei the Deathless in Sixty Seconds
- He can't die yet. Hidden Death means dropping him to 0 only stuns the table, not the boss. Make sure the players have a clue that a needle (egg/duck/hare/oak) ends him for real before you start the fight.
- Open with Withering Word. Throw the death-curse at the lowest-AC caster turn one; recharge it on a 5–6 and re-fire whenever it's up.
- Kill-priority for the party is the needle, not Koschei. If you want a single-room brawl, place the needle as AC 13 / 10 hp in the room and let them connect the dots.
- When bloodied (68 hp), go evasive. Use Deathless Step every time you take damage and spend legendary actions on Frost of the Grave to slow the swarm closing on you.
- Three ways to run him: as a true unkillable arc-villain (needle is a separate quest), as a single-encounter puzzle-boss (needle in the room), or as a flagship paired with the Strzyga for a brutal two-front terror fight.
Koschei the Deathless
Large undead, neutral evil
CR 8 · 3,900 XP · GUIDELINEHidden Death. Koschei's soul is sealed in a needle hidden far away (inside an egg, inside a duck, inside a hare). While that needle exists, Koschei cannot die: when he is reduced to 0 hit points he instead drops to 1 hit point and gains no benefit from being hit further for the rest of that turn. Only by breaking the needle (a separate quest object the DM places in the world) can the heroes end him for good. If you want a one-fight version, let the players learn the needle is in the room and treat it as AC 13, 10 hp.
Undying Vigor. If Koschei takes 25 damage or less from a single source, and that damage would reduce him to 0 hit points, he is reduced to 1 hit point instead (this is in addition to Hidden Death and resolves automatically).
Dread Command. Undead within 30 feet of Koschei that can hear him have advantage on saving throws against effects that turn undead, and deal an extra 3 (1d6) necrotic damage with their weapon attacks.
Actions
Multiattack. Koschei makes two attacks with his Boyar Spear, or one Boyar Spear attack and casts a spell from Withering Word.
Boyar Spear. Melee Weapon Attack: +8 to hit, reach 10 ft., one target. Hit: 14 (2d8+5) piercing damage plus 7 (2d6) necrotic damage, and the target must succeed on a DC 15 Constitution saving throw or its hit point maximum is reduced by the necrotic damage taken until it finishes a long rest.
Withering Word (Recharge 5–6). Koschei speaks a death-curse at one creature he can see within 60 feet. The target must make a DC 15 Wisdom saving throw, taking 31 (7d8) necrotic damage on a failure, or half as much on a success. A creature reduced to 0 hit points by this effect that is not killed outright is paralyzed (as if frozen) until the start of Koschei's next turn.
Bonus Actions & Reactions
Deathless Step (Reaction). When Koschei takes damage, he can teleport up to 30 feet to an unoccupied space he can see, leaving a wisp of grave-frost behind.
Legendary Actions (3/Round)
Spear Sweep. Koschei makes one Boyar Spear attack.
Frost of the Grave (Costs 2 Actions). Each creature within 15 feet of Koschei must succeed on a DC 15 Constitution saving throw or take 10 (3d6) cold damage and have its speed halved until the end of its next turn.
Cruel Whisper (Costs 2 Actions). Koschei targets one creature he can see within 60 feet. It must succeed on a DC 15 Wisdom saving throw or be frightened of him until the end of its next turn.
A towering, horn-crowned revenant of fang and gristle, bare-chested and scarred, he grips a tall boyar's spear and a ringed war-shield while a tattered cloak drags through the frost. His grin never fades, because he knows no blade in the room can truly kill him.
Koschei the Deathless, Bound
Companion · acts on your initiative
Bound · GUIDELINETwin Soul (signature). Koschei the Deathless has two hearts and two souls; the first time she would drop to 0 hit points each day, she instead drops to 1 hit point and rises shrieking with renewed hunger.
Actions
Rending Talons. Melee Weapon Attack: +6 to hit, reach 5 ft., one target. Hit: 11 (2d6+4) slashing damage, and the target can't regain hit points until the start of the Strzyga's next turn.
Reactions
Night-Owl Lunge. When a creature within 5 feet of the Strzyga regains hit points, she can move up to half her speed toward that creature without provoking opportunity attacks.
A vampiric owl-fiend of Slavic night, she answers Koschei's call for the promise of terror-thick blood, circling above the battle on silent wings.
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 Withering Word on the squishiest caster, then spear the front-liner who keeps healing. He cannot die while the needle exists, so a low party should be hunting that object, not grinding his hit points. Pair him with the Strzyga only as a terrifying set-piece reveal, not a fair fight.
This is his home fight: open with Withering Word, then spend legendary actions on Frost of the Grave when the party clusters to gang him. Kill-priority is healers (his spear drops max HP) and anyone carrying the needle. Let him gloat through Undying Vigor and Hidden Death so the table realizes the needle is the real boss.
Lead with Withering Word, Multiattack the tank, and Deathless Step away from any grapple or zone. Burn Cruel Whisper to peel off the rogue before they reach the needle. Kill-priority is whoever is sprinting for the hidden soul; ignore the meat-shields.
Put Koschei the Deathless 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 Koschei the Deathless?
Natively CR 8 (3,900 XP) as a solo Tier-2 boss for a party of levels 5–10, with legendary actions and a reaction. The block also scales to CR ~2 at Tier 1 and CR ~11 at Tier 3 using the numbers in the tiers table; only the numbers move, the traits stay the same.
Can Koschei the Deathless be a companion or ally?
He is built as an adversary boss, but a DM can reskin him as a grim deathless patron who lends the party his bound Strzyga (AC 14, 82 hp) or even fights beside them against a greater horror, using his native-tier numbers without the band-drop.
How do the players actually kill him?
By finding and breaking the needle that holds his soul (hidden in an egg, in a duck, in a hare, in a chest, beneath an oak). Until that needle is destroyed, Hidden Death keeps standing him back up at 1 hit point; once it shatters, he loses Hidden Death and Undying Vigor and dies normally.
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 Koschei the Deathless 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