Riddles at the Peak

One-Shot · 4–5 Players · Average Level 6 · ~3.5 Hours · Greek Mythology

Style: Mythic Quest — Social / Avoidance / Boss Combat | Win Condition: Pacify or defeat the sphinx Arkteia; re-open the mountain trade routes through Theron | Setting: Trireme at sea → forested island crossroads → crumbling mountain-top oracle temple.

The ancient gynosphinx Arkteia has awakened beneath Mount Theron's summit ruins, devouring those who cannot answer her riddles. Sea captain Nikias of Piraeus — sole survivor of a prior expedition — hires the party, hands over a water-stained parchment recovered from his last crew's wreck, and offers passage.

Nikias, hiring the party: "She will ask you something. Answer well." — the parchment reads only: "Three truths wake what one lie cannot," above three circles (⊙ ⊙ ⊙) and a wavy line. Presenting it to Arkteia triggers the Right of the Riddled (see Encounter 3) — without it, she attacks on sight.

Major Beats

Nikias hires the party at a coastal tavern, hands over the parchment, offers passage aboard his trireme.
The Siren Shores: 3 Sirens sing from sea rocks as the trireme rounds Theron's headland — navigate, counter the song, or fight.
The Crossroads Standoff: A centaur warband blocks the mountain road. Atalanta is in a standoff with chieftain Eurytion over her stolen silver arrow — negotiate, trick, or fight; recruit Atalanta if her arrow is returned.
The Ascent: mountain path to the temple; Atalanta (if recruited) briefs the party on the sphinx's habits.
The Riddle at the Peak: Arkteia and 2 Manticores await. Defeat her, answer three riddles, or solve her logic puzzle.
Resolution: the party returns to Nikias with proof of victory, a compact of passage, or a secret Arkteia chose to share.

Creature / Enemy List

Creature	Easy	Med	Hard	Notes
Siren	1	3	4	Enc. 1; fully avoidable
Centaur	2	4	6	Enc. 2; avoidable via RP/checks
Eurytion, Chieftain	—	1	1+	Enc. 2; avoidable; does not flee
Manticore	1	2	3	Enc. 3; sphinx's guardians
Arkteia (Sphinx)	1 (adj.)	1 (buffed)		Enc. 3 boss — see scaling
Atalanta	—			Recruitable ally, Enc. 2; fights Enc. 3

Difficulty Scaling — Session Overview

Encounter	Easy (APL 5–6)	Medium (APL 7, baseline)	Hard (APL 8–9)
1 — Shores	1 Siren, DC 12, crew safe below deck	3 Sirens, DC 14–15 avoidance	4 Sirens, crew at risk regardless, no recharge on Dirge
2 — Crossroads	2 Centaurs, Persuasion DC 11	Baseline as written	6 Centaurs, Eurytion 2× Leg. Resist., 2 reinforcements rd 2
3 — Sphinx	Arkteia CR 8 (115 HP), 1 Manticore, no Leg. Resist.	Arkteia CR 10 (145 HP), 2 Manticores	Arkteia CR 11 (175 HP), 3 Manticores, minor deity takes note if killed

World detail: Eurytion's saddlebag holds 3× Javelins of Lightning (+1d6 lightning on hit, single use). A centaur scout's map shows two hidden side paths into the temple ring — useful terrain flavor for Encounter 3. Encounter 1 is fully optional and can be dropped without plot impact if time is short.

Secrets: Nikias is missing two fingers; the sphinx spared him and he doesn't know why (deep shame, won't discuss it). Atalanta was tasked by Artemis to watch the sphinx and intervene only as a last resort — more conflicted than she admits. Arkteia secretly yearns to return to slumber; violence is her last preference, but pride keeps her from saying so.

Encounter 1 — The Siren Shores

Easy (avoided) / Medium (combat) · ~25–35 min · ~3–5 rounds if combat | Terrain: Trireme deck ~60×20 ft; sirens on rocks 60–100 ft.

3× Sirens sing from the rocks as the trireme rounds the headland; 6 unprotected crew NPCs will walk to the rail if the song isn't countered. Win: pass without ship damage or losing crew.

Options: skill challenge (3 successes before 3 fails), creative RP solutions, or flee wide (+1 hr travel).
Sails AC 10/30 HP — destroyed sails cost an extra hour rowing (forfeits short rest before Enc. 2). Crashing waves: prone near the rail → DC 12 STR or fall overboard.
Alluring Song (combat): 60 ft, DC 15 WIS each turn or Charmed (moves toward nearest Siren, can't retreat). Captivating Dirge (recharge 5–6): DC 15 WIS or Stunned — can knock an edge-adjacent creature off.
Reaction Haunting Melody: hit a Siren → DC 13 WIS or disadvantage on attacks until end of next turn.

Encounter 2 — The Centaur's Crossroads

Easy (negotiated) / Moderate (combat) · ~30–40 min · ~4–6 rounds | Terrain: Forest crossroads ~80×60 ft, 10-ft road

4× Centaurs + chieftain Eurytion block the road; Atalanta stands opposite in a tense standoff over her stolen silver arrow. Win: gain passage; optionally recruit Atalanta.

Negotiate Eurytion: DC 13 Persuasion (vow to riddle-challenge, not fight); DC 14 History/Religion (cite the old protocol, +2 next check); DC 14 Intimidation (call him a coward — fail starts combat immediately); DC 12 Sleight of Hand to swap the arrow (needs a simultaneous DC 13 Performance/DC 14 Deception distraction). Showing the parchment = auto-pass (doesn't return the arrow alone).
Recruit Atalanta: only if her arrow is returned (persuasion, theft, or combat) — won't join if party sides against her or attacks/demeans her. She then briefs the party on the temple.
Non-combat: Trial of Strength (best 2/3 contested Athletics, centaur +4); wine tribute (advantage on Persuasion); invoking Artemis (Atalanta vouches, DC drops to 10).
If fought: Eurytion opens with War Shout (advantage to all Centaurs), Charges. Centaurs surrender at 25% HP if he's down; he fights to 0.

Encounter 3 — The Sphinx of Mount Theron (Boss)

Hard (baseline) / Deadly (scaled) · ~60–75 min combat / ~20–30 min riddle-only · ~5–8 rounds | Terrain: Open temple ring, ~80×80 ft, roofless

Arkteia sits on a shattered altar, 2 Manticores pacing the perimeter. 3 win paths: (A) reduce her to 0 HP; (B) answer 3 riddles (pre-combat via parchment, or accumulated via Riddle of Fate — best outcome, boon granted); (C) solve her logic puzzle at 50% HP (neutral — she relocates, unharmed).

With parchment: she invokes the Right of the Riddled — no attacks until 3 riddles posed/answered. Without: roll initiative immediately; producing it mid-fight only pauses her the following round if she hasn't used Multiattack yet.
Terrain: 12 columns (3/4 cover, togglable DC 18 Athletics, 3d10 bludgeoning line, DC 14 DEX half). Edge drop: DC 15 DEX or hang (pull up DC 14 Athletics; fall = 5d6). Oracle Basin: DC 14 Arcana grants advantage on next riddle answer, once/encounter.
Phase 1 (145→73 HP): Riddle of Fate on recharge; Legendary priority Claw→Sandstorm Veil→Prophetic Judgment. Manticores volley Tail Spikes from range.
Phase 2 (72→1 HP): takes to the air (grapple needs 2× contested DC 15 STR); at exactly 50% HP she halts and offers the puzzle once. Manticores shift to melee/grapple toward the edge.
Riddle of Fate (recharge 5–6, mid-combat): target answers next turn (allies assist DC 12 INT History as reaction for advantage); correct = regain 2d8 HP; wrong/none = 7d8 psychic, DC 16 INT half.

Best resolution: all 3 riddles correct → Arkteia stands down fully, reveals the tomb beneath the altar, and grants a lasting boon.

Creature Stat Blocks

Siren

Medium Fey, CN · CR 3 (700 XP)

AC 13 | HP 52 (8d8+16) | Speed 30 ft., Fly 50 ft., Swim 40 ft.

CHA 20(+5) — Performance +9. Vulnerable: Fire. Darkvision 60 ft.

Alluring Song. 60 ft, DC 15 WIS each turn or Charmed (must approach).

Multiattack. 2× Talon +5 (7, 1d6+4 slashing). Captivating Dirge (recharge 5–6) 120 ft, DC 15 WIS or Stunned. Reaction: Haunting Melody — hit attacker, DC 13 WIS or disadvantage.

Centaur

Large Monstrosity, NG · CR 2 (450 XP)

AC 12 | HP 45 (6d10+12) | Speed 50 ft.

STR 18(+4) — Athletics +6.

Charge. 30+ ft. + Pike hit → DC 14 STR or prone.

Multiattack. Pike +6 (9, 1d10+4) + 2× Hooves +6 (11, 2d6+4). Javelin +6, 30/120 ft, 7 (1d6+4).

Eurytion, Centaur Chieftain

Large Monstrosity, LN · CR 4 (1,100 XP)

AC 14 | HP 95 (10d10+40) | Speed 50 ft.

STR 20(+5) — Athletics +7, Intimidation +4.

Charge. DC 16 STR or prone + pushed 10 ft. Herd Commander: Centaurs within 60 ft. +2 AC while he's conscious.

Multiattack. Pike +7 (11) + 2× Hooves +7 (12), or 2× Javelin +7 (8). BA: War Shout (recharge 5–6) — Centaurs within 60 ft. advantage on attacks. Reaction: Trample — Hooves attack vs. anyone moving away within 10 ft.

🏹 Atalanta

Medium Humanoid, NG · CR 6 (2,300 XP) · Recruitable Ally

AC 15 | HP 78 (12d8+24) | Speed 35 ft.

DEX 20(+5) — Acrobatics +8, Perception +9, Stealth +8.

Favored of Artemis: ignores natural difficult terrain, no long-range disadvantage. Hunter's Instinct: always knows a visible creature's HP category.

Multiattack. 2× Shortbow + 1 Shortsword, or 3× Shortbow, all +8 (8, 1d6+5). Silver Arrow (1/day) +8, +10 (3d6) radiant, ignores piercing resistance, target disadvantage on attacks. BA: Hunter's Mark +3 (1d6) extra vs. marked target.

Arkteia, the Sphinx

Large Monstrosity, LN · CR 10 (5,900 XP) · Boss

AC 17 | HP 145 | Speed 40 ft., Fly 60 ft.

STR 24(+7)/INT 20(+5)/WIS 18(+4)/CHA 18(+4) — Arcana/History/Religion +9. Immune: Psychic, nonmagical B-P-S, Charmed, Frightened. Truesight 120 ft.

Inscrutable (immune to mind-read/divination). Legendary Resistance (3/day). Riddle's Grace: correct answerer gets advantage vs. her abilities (1 hr), her attacks vs. them at disadvantage. Truth-Seeker: detects lies told in the last 24 hrs.

Multiattack. 2× Claw +10 (15, 2d8+6); both hit same target → free Bite +10 (22, 3d10+6). Riddle of Fate (recharge 5–6) — see mechanics. Paralyzing Roar (recharge 6, Phase 2: 5–6) 60 ft, DC 16 CON or Frightened+Stunned.

Legendary (3/rd): Claw Attack (1), Sandstorm Veil (2, 15 ft, DC 15 DEX or Blinded), Prophetic Judgment (3, 120 ft, DC 17 WIS or Paralyzed).

Manticore

Large Monstrosity, LE · CR 3 (700 XP)

AC 14 | HP 68 (8d10+24) | Speed 30 ft., Fly 50 ft.

STR/DEX/CON 17/16/17. Darkvision 60 ft.

Tail Spike Supply: 24 spikes, refills on long rest.

Multiattack. Bite +5 (7) + 2× Claw +5 (6), or Bite + 2× Tail Spike +5 (7, 100/200 ft).

Key Prop & Riddle Reference

📜 The Parchment

Physical Handout · Given by Nikias

Reads only: "Three truths wake what one lie cannot," above three circles (⊙ ⊙ ⊙) and a wavy line. Print or hand-write on tea-stained paper — this is the entire written content.

Enc. 2: shown to Eurytion, recognized as the ancient Compact of Passage — grants passage but not the arrow alone.

Enc. 3: presented visibly triggers the Right of the Riddled — Arkteia poses 3 riddles before any violence.

Riddle Bank — Selection Guide

Choose 1 Easy, 1 Medium, 1 Hard for the Right of the Riddled; any may double as a mid-combat Riddle of Fate. Give players 60 real seconds; accept reasonable near-answers.

Easy: "The more of me you take, the more you leave behind" → Footsteps. "Cities but no houses, mountains but no trees, water with no fish" → A Map. "I speak without a tongue, hear without ears" → An Echo.

(7 additional Medium/Hard riddles exist in the full digital session guide's Riddle Bank — select per DM Guidance above.)

Win-Path Loot

Three Truths (best): Arkteia reveals the tomb beneath the altar and grants a lasting boon.

Combat Victory: she goes dormant (stone-cracks form); routes open; minor divine consequence possible (a deity may take note at Hard scaling).

The Puzzle: she agrees to relocate off the trade routes — neutral, she remains unharmed and unwon.

Eurytion's saddlebag: 3× Javelins of Lightning (+1d6 lightning, single use each).

Terrain Prop — Centaur Scout's Map

Found on Eurytion (Enc. 2 loot): shows two narrow side paths leading to hidden entrances on the east and west sides of the summit temple ring — usable as an alternate approach in Encounter 3.

NPC Quick Reference

🧭 Nikias of Piraeus

Quest Giver · Aging Sea Captain

Appearance: missing two fingers on his left hand — visible reminder of his encounter with Arkteia.

Offer: passage aboard his trireme + 500 gp for a resolution.

Secret: the sphinx spared him and he has no idea why — deeply ashamed, won't discuss it.

Line: "She will ask you something. Answer well."

🏹 Atalanta — Roleplay Notes

Legendary Huntress · Recruitable Ally, Encounter 2

Motivation: the silver arrow was a gift from Artemis herself; furious but controlled — won't attack a melee she can't win alone.

Secret: Artemis tasked her to watch the sphinx and intervene only as a last resort — more conflicted about the mission than she lets on.

If recruited: "She will ask you three things. Answer truly, all three. That is what the old stories say." — targets Arkteia with Silver Arrow unless told otherwise.

If not recruited: Encounter 3 becomes one step harder; may arrive as a last-moment emergency intervention at DM discretion if the party is wiped.

🦁 Arkteia — Roleplay Notes

Ancient Gynosphinx · Antagonist / Boss

Motivation: awakened by miners disturbing her resting place; tests mortals because she believes only the wise deserve passage — not purely malevolent.

Secret: yearns to return to slumber; violence is genuinely her last preference, but she's too proud to admit it.

Opening line: "I have waited long enough for someone interesting. Let us see if you qualify."

Resolution & Aftermath

The party returns to Nikias with one of: proof of Arkteia's defeat, a signed compact of passage, or a secret she chose to share only with those who earned her respect.

Atalanta, if recruited and kept alive, may continue with the party beyond the session at DM discretion.