Secret Floors Guide (Hidden Chambers)

Enter the Gungeon has a hidden chamber between each main floor (1.5 through 4.5). Defeating any secret floor boss flawlessly does not reward a Mistrzowski nabój. This guide covers the requirements, step-by-step access, important notes, and first-visit rewards for each one.

Oubliette

Located between Twierdza Władcy Ołowiu and Właściwy Loch Giwer. Sewer-style layout full of garbage bags, toxic puddles, and harmless Nabojak variants.

Cost: 2 keys (or Zaufane wytrychy / Wiertło as substitutes)

Steps to enter

1. Twierdza Władcy Ołowiu always contains a fireplace room — find the blue water barrel inside or in an adjacent room
2. Push the barrel next to the fireplace to extinguish the flames
3. Crawl into the fireplace and interact with the hidden switch
4. A hidden room with a trapdoor appears on the map — the trapdoor has two locks, each costing 1 key (2 total); Zaufane wytrychy or a Wiertło can substitute for normal keys

Notes

• Water barrels are fragile — enemy attacks and explosions destroy them, so position carefully during room clear
• If the barrel is gone, use Megaspryskiwacz, Rozpylacz chłodziwa
• After your first visit, the water barrel usually spawns inside or directly adjacent to the fireplace room on all future runs

Rewards and unlocks

• A small fixed room inside the Oubliette always contains the Stary herb, required for the Opactwo Prawdziwej Giwery
• First visit unlocks Działo śmieciowe

Opactwo Prawdziwej Giwery

Located between Właściwy Loch Giwer and Kopalnia czarnego prochu. Gothic monastery aesthetic with stronger enemies than the surface floors.

Cost: must first complete the Oubliette and retrieve the Stary herb

Steps to enter

1. Pick up the Stary herb from its fixed room inside the Oubliette — it occupies an armor slot and disappears the moment you take any damage
2. Carry the Stary herb through the rest of the Oubliette and all of Właściwy Loch Giwer without being hit
3. Find the altar room on Właściwy Loch Giwer — it contains seven large bullet warrior statues and looks one cell larger than a normal room on the map; it tends to appear near a shop or chest room
4. Place the Stary herb on the altar to open a staircase leading into the Opactwo Prawdziwej Giwery

Notes

• Any hit destroys the Stary herb — if you're already low on health when entering the Oubliette, consider whether the escort is realistic
• Some rooms inside the Opactwo Prawdziwej Giwery contain permanently Jammed enemies regardless of your Curse level — they deal and take significantly more damage
• The Opactwo Prawdziwej Giwery always has a hidden room containing Poszukiwacz prawdy – Brother Albern; opening his chest yields Kłamstwa. This room spawns independently from normal secret room generation, so multiple secret rooms in one Opactwo Prawdziwej Giwery run are common

Rewards and unlocks

• Boss drops both a normal boss reward and a Synergy Chest
• Simply entering for the first time unlocks Krwawa brosza and the "Reverence for the Dead" achievement — you do not need to clear the floor

Resourceful Rat's Lair

Located between Kopalnia czarnego prochu and Hollow. Mine tunnel layout with no shops and no normal chest rooms. The most complex prerequisites — plan ahead across multiple runs.

Cost: Nadgryziony klucz + 1 Klucz + 2 Ślepaks (the Klucz can be swapped for Zabójczy wytrych, Kluczosznikow-47, or Zaufane wytrychy; the Nadgryziony klucz has no substitute)

Preparation

• Hard prerequisite: the Nadgryziony klucz does not spawn in the shop at all until you have built the Nabój Zdolny Zabić Przeszłość. You have to finish the four-component run in Bullet That Can Kill the Past Guide before this route opens up
• The Nadgryziony klucz first appears in a Właściwy Loch Giwer shop for 1000 Łuski; payment can be made in installments across runs, and once paid in full it costs 115 Łuski on every later run. Discount items never lower its price
• The Nadgryziony klucz can be stolen, but not with Kotwiczka or the Cztery strony świata hook (see How to Steal from Shops); if stolen before it has been paid off once, it returns next run at the price it was at
• Six Denerwująca notatka are scattered throughout all floors of Enter the Gungeon and appear randomly each run — pick them up whenever they show up. Each note ends with a cheese-wedge arrow indicating one direction in the maze; the more notes you have collected, the more of the correct sequence you know before entering the Lair

Steps to enter

1. On Kopalnia czarnego prochu, find a room with 2–4 rats running on the ground and clear it
2. Reveal the hidden trapdoor by walking repeatedly over suspicious floor tiles (a larger-than-normal dust cloud marks the right tile), spraying liquid on the ground, or using a Ślepak anywhere in the room — short-range blank effects like Ślepe naboje won't work, and the trapdoor never spawns in a shop room
3. Open the trapdoor with a Klucz and drop in
4. Walk along the minecart tracks to the end — do not ride the minecart (riding teleports you backwards repeatedly; walking is faster)
5. Use one Ślepak at the dead end to open the first hidden passage. If you have Pancerz, deliberately falling into the nearby pit reveals this passage too, saving a Ślepak
6. Walk to the next dead end and use a second Ślepak to open the second hidden passage. This one counts as a separate room with no pit, so the second Ślepak cannot be saved unless you have another way to hurt yourself
7. Open the final hatch with the Nadgryziony klucz to enter the Lair

Notes

• Zakrwawiony szalik lets you teleport past both hidden passages, skipping both Ślepaks
• The Lair shows only a rat-holding-cheese animation instead of a real map
• Candle-carrying rats wander the floors — harmless normally (they die on contact and sometimes drop Łuski), but become Jammed and deal contact damage if you carry any Curse
• The maze is a sequence of six rooms, each with a choice of exit direction. Wrong once: sent back to the previous room. Wrong twice: elevator to the Hollow, ending your Lair run
• The correct sequence is fixed per save file and stays the same forever once discovered

Rewards and unlocks

• After defeating the Zmyślny Szczur, the reward room has eight pedestals with Serduszkos, Pancerz, Kluczs, Ślepaks, Szklany kamień Guon, and Amunicja
• Four special chests in the room require Klucz szczuras and contain Elimentaler, Nadgryziony ser, Worek Zmyślnego, and Szczurze kamasze. Klucz szczuras only drop during the third Punch-Out phase of the fight, up to six per fight
• The reward room also has a secret room with a snake hidden behind two locked doors — items can be dropped through the second door, so only one Klucz szczura is needed to feed it
• Feed the snake 4 guns or items and it follows you as a companion until the Giwerna fight, where it defects and is absorbed to trigger the Advanced Dragun. That is the route to Ślepakowy Graal and the "Advanced Slayer" achievement (the other is throwing a Dziwne jajo into fire)
• The snake refuses Zepsuty telewizor, Gąbka, and Zaufane wytrychy — do not count on those to make up the four
• Alternatively, you can kick the Zmyślny Szczur into the snake to feed it
• After the reward room you can proceed to the Hollow normally, or spend a Klucz szczura to skip directly to the Kuźnia
• First visit unlocks Dziwne jajo

R&G Dept.

Located between Hollow and Kuźnia. No connection to the other secret floors.

Cost: 1 Mistrzowski nabój + 2 guns or items (sold to the Skupujący pełzacz in Hollow)

Steps to enter

1. Find the Skupujący pełzacz in Hollow
2. Sell the Mistrzowski nabój and 2 items — the entrance opens immediately after the third item is sold, so sell the Mistrzowski nabój last if you want to keep trading first

Notes

• The cost is steep: a Mistrzowski nabój proves you cleared a boss without damage, and you lose two usable items on top of that
• R&G Dept. has no shop and sparse pickups
• The map outline is deliberately shaped like a handgun; after beating Spluwa there is no exit elevator — you have to throw yourself off the rooftop arena to reach the Kuźnia
• Only enter when your loadout has clear surplus — if your core weapon or survivability items are borderline, selling them for a bonus floor rarely pays off