On Thin Ice decision guide: Boss Fights & Key Choices - Choices

On Thin Ice decision guide: Boss Fights & Key Choices

Use this On Thin Ice decision guide to prepare at Marlin Coast, defeat Caranthir and Eredin, avoid missable issues, and claim the quest rewards.

2026-09-23
On Thin Ice Wiki Team
Quick Guide
  • On Thin Ice decision guide: Prepare before speaking with Avallac'h beside the boat.
  • Point of no return: The battle begins when you tell Avallac'h you are ready.
  • Caranthir strategy: Use Quen, control distance, and surface quickly after the underwater sequence.
  • Eredin strategy: Punish ranged attacks, follow the portal, and save stamina for the final phase.
  • Quest rewards: Expect 500 XP, Hav'caaren, and a Lesser Glyph of Aard.

On Thin Ice Decision Guide: Preparation

On Thin Ice is a main quest in The Witcher 3: Wild Hunt, taking place at a Nilfgaardian camp on Marlin Coast before the final battles against the Wild Hunt. The most important decision is not a dialogue branch: it is choosing when to speak with Avallac'h beside the boat and begin the battle.

Before starting, finish any short preparation tasks you still need. The camp's quartermaster can provide repairs and blacksmith services, while nearby buildings contain useful ingredients and weapons. These services are available before the battle, but the camp will no longer function normally afterward.

Repair and Refill

Repair equipped weapons and armor, restock healing items, and prepare combat potions before triggering the battle.

Check Side Content

Travel remains possible until you speak with Avallac'h beside the boat, so finish urgent contracts and errands first.

Protect Your Save

Create a manual save before beginning. It gives you a safer recovery point if a boss glitch occurs.

PreparationWhy It MattersRecommended Action
Weapon conditionBoss fights punish weak damage outputRepair before the battle
Alchemy suppliesPotions and bombs support both encountersBrew and refill beforehand
Inventory spaceQuest rewards include a sword and glyphLeave room for loot
Side questsThe battle changes the camp stateFinish urgent tasks first
Avoid Accidental Theft

Do not loot outdoor containers or interact with suspicious camp objects while soldiers are nearby. Stealing can cause Nilfgaardian soldiers to attack, even though it does not normally fail the quest.

Battle Start and Ciri's Route

When you are ready, speak with Avallac'h at the boat. Ciri is not allowed to join the initial battle plan regardless of earlier dialogue choices, but the situation changes once Caranthir freezes the allied forces. You then control Ciri and must push through Wild Hunt enemies toward the general.

1

Prepare at the Camp

Repair gear, organize the inventory, and use your preferred potions before talking to Avallac'h. This is the final convenient preparation window.

2

Trigger the Battle

Speak with Avallac'h beside the boat when you are ready. The Sunstone is used, the Naglfar is summoned, and the battle sequence begins.

3

Advance as Ciri

Move forward through the Wild Hunt groups. Ciri's Elder Blood power makes these enemies highly manageable, and Blink can clear several targets at once.

4

Reach Caranthir

Do not waste time trying to clear every enemy. Groups can continue spawning, so focus on reaching Caranthir and reducing his health until the cutscene begins.

PhaseCharacterMain ObjectiveBest Approach
CampGeraltPrepare for battleRepair, restock, save
First assaultCiriReach CaranthirMove forward and use Blink
TransitionCiriBreak the staff orbDamage Caranthir until the scene triggers
Next phaseGeraltDefeat CaranthirControl distance and avoid elemental pressure
Do Not Farm the First Wave

The Wild Hunt enemies during Ciri's section can continue appearing. Clearing every opponent adds risk without advancing the objective, so keep moving toward Caranthir.

Caranthir Boss Fight and Escape

Caranthir's encounter has two connected parts. Ciri first weakens him and breaks the orb on his staff. Geralt then takes over for the main fight, where Caranthir uses teleportation, magic projectiles, and Ice Elementals.

Quen provides a useful safety layer against sudden projectiles, while Yrden and Magic Trap can help limit the pressure around Geralt. Keep enough space to read Caranthir's teleport patterns. If an Ice Elemental approaches, reposition so it can interfere with Caranthir's line of sight; his attacks can damage his own summoned allies.

ThreatWarning SignResponse
Magic projectilesCaranthir creates distanceKeep moving and maintain Quen
TeleportationBoss disappears from melee rangeAvoid chasing blindly; reset your position
Ice ElementalsAdds close in from the arenaUse distance and let attacks collide with them
Underwater escapeThe arena changes after the defeat sceneSwim upward immediately

After Caranthir's health is nearly depleted, a cutscene sends both characters underwater. The objective changes to reaching the surface. Swim upward without detouring; Killer Whale can provide additional breathing room if it is available.

Resource Management

You can meditate after the Caranthir fight without losing meaningful time before the next major encounter. Use this opportunity to restore your preparation instead of saving every potion or bomb.

Reaching and Defeating Eredin

After resurfacing, move toward the Naglfar. Several enemies along the route can continue spawning, so clear only the targets blocking your path. Encounters with Udalryk and Hjalmar are part of the approach, but the priority is reaching the ship.

Eredin's fight rewards patience. He teleports like Caranthir, attacks with magic at range, and switches to sword attacks when Geralt closes in. He can be staggered, but repeated attacks may be parried if used without timing.

Quen and Patience

Maintain a defensive layer and wait for openings after Eredin's ranged attacks. Avoid forcing a long melee exchange.

Controlled Damage

Rend can deliver reliable pressure when used without excessive charging. Whirl is effective when activated at a safe opening.

Portal Awareness

Follow Eredin through every portal and watch for falling magic projectiles during the final return to the Naglfar.

Eredin PhaseKey DangerPractical Response
Naglfar arenaTeleports and sword parriesStrike after ranged attacks
Icy plateauForced relocationReorient quickly and continue the duel
Return portalFalling magic projectilesReach the portal without delay
Final exchangeScripted finishing sequenceContinue attacking until the cutscene starts

Final Battle Checklist:

  • Repair weapons and armor before speaking with Avallac'h
  • Complete urgent side content before triggering the battle
  • Defeat Caranthir and swim directly to the surface
  • Follow Eredin through the portal and avoid falling projectiles
  • Collect the quest rewards before continuing to the next quest
Possible Boss Progression Glitches

Caranthir may occasionally stop responding after control shifts from Ciri to Geralt. Reloading the previous checkpoint is the recommended first response. If Eredin is defeated unusually quickly, the next scripted portal may take time to appear.

Rewards, Bugs, and FAQ

Completing On Thin Ice ends the battle with Eredin and leads directly into Tedd Deireadh, The Final Age. The listed rewards are 500 XP, the Hav'caaren sword, and a Lesser Glyph of Aard. The quest also closes the Marlin Coast camp state, so collect anything important before starting the battle.

RewardTypeWhen It Appears
500 XPExperienceQuest completion
Hav'caarenSwordQuest completion
Lesser Glyph of AardGlyphQuest completion
Next questStory progressionAfter the ending sequence

For additional quest objectives and the full journal context, consult the On Thin Ice quest reference. The page also documents known issues involving Caranthir, Eredin, camp interactions, and unusual enemy spawns.

Quest Outcome

On Thin Ice does not present a major branching dialogue choice at the camp. The meaningful decision is when to begin the battle, because speaking with Avallac'h removes the preparation window.

Q: What is the point of no return in On Thin Ice?

Speaking with Avallac'h beside the boat begins the battle. Travel and preparation remain available until that conversation.

Q: Can Ciri fight in the opening battle?

Avallac'h does not allow Ciri to join the planned assault, regardless of dialogue choices. She takes control later after Caranthir freezes the allies.

Q: What is the safest way to defeat Caranthir?

Use Quen, keep distance from his projectiles, let Ice Elementals obstruct his attacks when possible, and swim directly to the surface after the underwater scene.

Q: What rewards does this quest provide?

The quest grants 500 XP, the Hav'caaren sword, and a Lesser Glyph of Aard before the story continues into Tedd Deireadh, The Final Age.