How to trigger the hidden Fake Merchant boss fight in Slay the Spire 2 — the full Foul Potion chain, boss strategy, and the exclusive Merchant's Rug??? relic.
Slay the Spire 2 hides a secret boss fight behind a two-step event chain. If you find a Foul Potion from the Potion Courier event and then throw it at the Fake Merchant in a later Unknown room, the Merchant attacks you. Winning the fight rewards 300 gold, every knockoff relic in the Merchant's inventory, and the exclusive Merchant's Rug??? relic — the only way to obtain it in the entire game.
This guide covers the exact trigger chain, the boss fight mechanics, and why the fight is almost always worth taking when the opportunity appears.
Verification note
Cross-referenced across Kotaku, NeonLightsMedia, TheGamer, TPoseGaming, and GamerBlurb Fake Merchant guides. Trigger chain, rewards, and knockoff relic list confirmed by multiple independent sources.
Fast takeaway
This guide is built around one practical question, so you can use it during a run instead of digging through a broad overview.
If the answer depends on a mechanic, a character system, or a recent patch, the related links show you what to open next.
Use this when you want a direct answer instead of a broad overview.
Follow the related links if this decision depends on a mechanic, character system, or co-op rule.
Check the update pages whenever balance changes might shift the recommendation.
The Potion Courier is an Unknown room event where you find a courier collapsed on the ground with a batch of foul-smelling potions and a note addressed to a merchant. You are given two choices: take 3 Foul Potions, or take 1 random Uncommon Potion.
Always take the 3 Foul Potions if you plan to trigger the secret boss. One Foul Potion is consumed to start the fight, and the remaining two are usable in combat (they deal 12 damage to all enemies and 12 damage to you). Even if you never find the Fake Merchant, Foul Potions still function as cheap AoE damage items — they are not wasted.
The Fake Merchant appears as an Unknown room event in Act 2 or Act 3. The event looks like a normal shop, but the merchant's rug has a visible "For Sale" tag and all relics on display have "???" appended to their names. These are knockoff relics — weaker versions of real relics at roughly one-quarter of the normal shop price.
Without a Foul Potion, you can only buy knockoff relics at their discounted prices and leave. The knockoff relics are functional but weaker: Orichalcum??? grants 3 Block at end of turn (real: 6), Happy Flower??? grants energy every 5 turns (real: every 3). Buying them is rarely worth the gold.
When you have a Foul Potion in your inventory and encounter the Fake Merchant, an additional option appears: throw the Foul Potion at the Merchant. Selecting this option consumes one Foul Potion and initiates a combat encounter against The Merchant???.
The fight cannot be triggered any other way. If you sold or used all three Foul Potions before finding the Fake Merchant, the opportunity is lost for that run.
The Merchant??? has approximately 165 HP and fights at roughly the difficulty of an Act 3 elite or an easy boss. The Merchant attacks for 9-20+ damage per turn and has no complex phase transitions or instant-death mechanics. This is a straightforward damage race with moderately high incoming damage.
Compared to Act 3 elites like the Mecha Knight (300 HP, Artifact stacks, Strength scaling), the Merchant??? is significantly easier. Most decks that have reached Act 2-3 can handle this fight without major risk.
Defeating The Merchant??? is one of the most rewarding single encounters in the game. You receive three categories of rewards: gold, relics, and a card reward.
The Merchant's Rug??? is required for full Compendium completion. Because the relic can only be obtained through this specific event chain, completionists must successfully execute the Potion Courier into Fake Merchant into Foul Potion throw sequence at least once.
The Merchant's Rug??? is a callback to the original Slay the Spire, where the Merchant's rug was famously not for sale. In STS2, the bootleg Merchant displays a rug with a "For Sale" tag, and defeating him makes the rug yours — the punchline to a joke that started in 2017.
FAQ
The fight cannot be triggered without a Foul Potion. If you used or discarded all three, the Fake Merchant event becomes a normal knockoff relic shop with no boss fight option. Save at least one Foul Potion if you want to attempt the secret fight.
No. The Merchant's Rug??? has no gameplay effect. It exists purely for Compendium completion and as a trophy. It does not take up a meaningful relic slot in terms of gameplay impact — it simply fills the collection entry.
Based on community reports, the Fake Merchant event appears in Act 2 and Act 3 Unknown rooms. The Potion Courier event that gives Foul Potions can appear in any act, so obtaining the potion early and holding it until Act 2-3 is the intended sequence.
Sources
GamerBlurb: What The Fake Merchant Is
AuthorityFake Merchant encounter guide with knockoff relic comparison and boss fight strategy.
Kotaku: Secret Merchant Boss Fight
AuthorityFirst major coverage of the hidden Fake Merchant boss fight triggered by the Foul Potion.
NeonLightsMedia: Knockoff Relics and Foul Potion Secret
AuthorityDetailed Fake Merchant guide covering knockoff relic list, trigger chain, and reward breakdown.
TheGamer: Fake Merchant Secret Boss Fight And Rewards
AuthorityComplete Fake Merchant guide covering Potion Courier event, trigger conditions, and all rewards.
TPoseGaming: Fake Merchant Guide
AuthorityStep-by-step Fake Merchant boss trigger guide with Foul Potion acquisition details.