Karkinos at the Keel

Major Beats

1. Nereid herald + Coral Feast-Horn aboard mist-trireme.
2. Enc. 1: 3 sharks + octopus on oars.
3. Enc. 2: Thalassa parley / recruit (+ dolphin omen).
4. Enc. 3: Karkinos climbs the ram; Horn payoff.

Creature List

Difficulty

Creature / Enemy List

DM Tips

• As Written ★ — 6 Players, Average Level 8: Baseline for this guide. Numbers, DCs, and win tracks assume six PCs at average level 8.
• Easier: APL 4–6: reduce minion counts ~30%; DCs −2; boss loses one recharge or legendary option.
• Harder: APL 10–12: boss HP +25–35%; +1 legendary action; add a lieutenant or extra wave.

Encounter 1 — Blood in the Oar-Wash

• Oar banks: 4 zones (AC 12 / HP 12). If ≥3 destroyed → Short Rest only before Enc. 2; else Long Rest.
• Non-combat: Coral Feast-Horn + Animal Handling/Religion group challenge — 3 successes before 3 failures (DC 13) drives sharks off; octopus still must be cut free or contested Ath DC 14.
• Overboard: Ath DC 12 to climb ram/oar-ports; sharks get OA.
• Tip: Wondrous Item (maguffin), Unique

Encounter 2 — The Nymph’s Shoal

• Non-combat path: Show Coral Feast-Horn + Persuasion/Religion DC 14 (Insight DC 12 for advantage) → she believes you. Return pearl-net (Investigation DC 12 on ram) drops DC to 10.
• Combat path: Thalassa + spirits for 2 rounds or until she hits ½ HP, then flees.
• RECRUITMENT: Peaceful resolution → Thalassa aids Enc. 3; Delphinus arrives as omen.
• Tip: RECRUITMENT. Spare her shoal / return a stolen pearl-net (skill path) → she joins Enc. 3: once casts healing word and can use Help to expose Karkinos’s underbelly.
• Tip: RECRUITMENT. If not attacked: Persuasion DC 12 → one spirit warns when Karkinos will surface (party cannot be surprised in Enc. 3).
• Tip: Poseidon’s omen — appears if Thalassa is recruited or horn blown in Enc. 2

Encounter 3 — Karkinos Climbs (Boss)

• Win: 0 HP or ≤30 HP after a successful Coral Feast-Horn blow this fight (it plunges away).
• Horn payoff: incapacitate 1 round + soft underbelly (see item card).
• Ally: Thalassa Help / healing word; Delphinus rescues overboard PCs.
• Tip: Wondrous Item (maguffin), Unique
• Tip: RECRUITMENT. Spare her shoal / return a stolen pearl-net (skill path) → she joins Enc. 3: once casts healing word and can use Help to expose Karkinos’s underbelly.

DM Callouts

• Wondrous Item (maguffin), Unique
• RECRUITMENT. Spare her shoal / return a stolen pearl-net (skill path) → she joins Enc. 3: once casts healing word and can use Help to expose Karkinos’s underbelly.
• RECRUITMENT. If not attacked: Persuasion DC 12 → one spirit warns when Karkinos will surface (party cannot be surprised in Enc. 3).
• Poseidon’s omen — appears if Thalassa is recruited or horn blown in Enc. 2

Extra Encounter Detail (from session guide)

• Tip: Keep page-3 creature AC/HP lines visible while resolving Enc. 3.
• Tip: Favor non-combat paths in Enc. 1–2; Enc. 3 should still feel Hard.

Quick combat reference

• Hunting Shark — AC 12 | HP 45 (6d10+12) | Speed 0 ft., swim 40 ft. · Large Beast, Unaligned · CR 2 · Mini ×3
• Giant Octopus — AC 11 | HP 52 (8d10+8) | Speed 10 ft., swim 60 ft. · Large Beast, Unaligned · CR 1 · Mini ×1
• Thalassa (Sea Nymph) — AC 14 | HP 58 (9d8+18) | Speed 30 ft., swim 40 ft. · Medium Fey, Neutral · CR 3 · Mini: Sea/Water Nymph ×1
• Sea Spirit (Lesser Nereid) — AC 12 | HP 22 (5d8) | Speed 30 ft., swim 30 ft. · Medium Fey, Chaotic Neutral · CR 1/2 · Mini ×5
• Delphinus (Dolphin Ally) — AC 12 | HP 27 | Speed 0 ft., swim 60 ft. · Medium Beast, Neutral Good · CR 1/2 · Mini ×1
• Karkinos, Sacred Crab of Poseidon — AC 18 (natural) | HP 168 (16d12+64) | Speed 30 ft., swim 40 ft., climb 20 ft. · Huge Monstrosity, Neutral · CR 9 · BOSS · Mini: Cancer the C

Additional DM notes

• **Non-combat:** Coral Feast-Horn + Animal Handling/Religion group challenge — 3 successes before 3 failures (DC 13) drives sharks off; octopus still must be cut free or contested Ath DC 14.
• 18 (+4)**STR**13 (+1)**DEX**15 (+2)**CON**1 (−5)**INT**10 (+0)**WIS**4 (−3)**CHA
• Senses:** blindsight 30 ft. · Blood Frenzy: adv vs. creatures missing HP
• Hull Circler.** Can make opportunity attacks against creatures that leave the water within 5 ft. of the hull or ram.
• 17 (+3)**STR**13 (+1)**DEX**13 (+1)**CON**4 (−3)**INT**10 (+0)**WIS**4 (−3)**CHA
• Skills:** Stealth +5 · Hold Breath 1 hour on land
• Appearance:** small coral trumpet, warm and faintly pulsing
• Handout (22 words).** "When the sacred crab climbs for blood that is not the sea’s, sound this horn — hunger hears the true feast."
• Enc. 1–2.** Action: blow once (1/short rest) — sharks or octopus within 30 ft. make a DC 13 Wisdom save or end their next turn moving away from the hull.
• Enc. 3.** Action adjacent to Karkinos or at the bow rail: sound the true feast (once). Karkinos must succeed DC 15 Wisdom or be incapacitated until end of its next turn and lose Legendary Actions that round; soft underbelly exposed (attacks vs. it have advantage until it moves).

Pacing helpers

• Enc 1: End by ~45–50 min; if stuck, telegraph the non-combat path once.
• Enc 2: Spend recruitment / maguffin early so Enc 3 is not a blank check.

STAT BLOCKS

KEY ITEM / NPC

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