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 Munición maestra. This guide covers the requirements, step-by-step access, important notes, and first-visit rewards for each one.

Oubliette

Located between Fortaleza del Señor del Plomo and Armazmorra en sí. Sewer-style layout full of garbage bags, toxic puddles, and harmless Balín variants.

Cost: 2 keys (or Ganzúas fiables / Taladro as substitutes)

Steps to enter

1. Fortaleza del Señor del Plomo 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); Ganzúas fiables or a Taladro 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 Megarremojador, Fuga de refrigerante
• 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 Viejo blasón, required for the Abadía del Arma Verdadera
• First visit unlocks Cañón de basura

Abadía del Arma Verdadera

Located between Armazmorra en sí and Mina de pólvora. Gothic monastery aesthetic with stronger enemies than the surface floors.

Cost: must first complete the Oubliette and retrieve the Viejo blasón

Steps to enter

1. Pick up the Viejo blasón from its fixed room inside the Oubliette — it occupies an armor slot and disappears the moment you take any damage
2. Carry the Viejo blasón through the rest of the Oubliette and all of Armazmorra en sí without being hit
3. Find the altar room on Armazmorra en sí — 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 Viejo blasón on the altar to open a staircase leading into the Abadía del Arma Verdadera

Notes

• Any hit destroys the Viejo blasón — if you're already low on health when entering the Oubliette, consider whether the escort is realistic
• Some rooms inside the Abadía del Arma Verdadera contain permanently Jammed enemies regardless of your Curse level — they deal and take significantly more damage
• The Abadía del Arma Verdadera always has a hidden room containing Buscador de la verdad – Brother Albern; opening his chest yields Mentiras. This room spawns independently from normal secret room generation, so multiple secret rooms in one Abadía del Arma Verdadera run are common

Rewards and unlocks

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

Resourceful Rat's Lair

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

Cost: Llave roída + 1 Llave + 2 Fogueos (the Llave can be swapped for Llave armaestra, AKEY-47, or Ganzúas fiables; the Llave roída has no substitute)

Preparation

• Hard prerequisite: the Llave roída does not spawn in the shop at all until you have built the Bala que puede matar el pasado. You have to finish the four-component run in Bullet That Can Kill the Past Guide before this route opens up
• The Llave roída first appears in a Armazmorra en sí shop for 1000 Cartuchos; payment can be made in installments across runs, and once paid in full it costs 115 Cartuchos on every later run. Discount items never lower its price
• The Llave roída can be stolen, but not with Gancho or the Panel direccional 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 Nota exasperante 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 Mina de pólvora, 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 Fogueo anywhere in the room — short-range blank effects like Balas de fogueo won't work, and the trapdoor never spawns in a shop room
3. Open the trapdoor with a Llave 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 Fogueo at the dead end to open the first hidden passage. If you have Armadura, deliberately falling into the nearby pit reveals this passage too, saving a Fogueo
6. Walk to the next dead end and use a second Fogueo to open the second hidden passage. This one counts as a separate room with no pit, so the second Fogueo cannot be saved unless you have another way to hurt yourself
7. Open the final hatch with the Llave roída to enter the Lair

Notes

• Pañuelo ensangrentado lets you teleport past both hidden passages, skipping both Fogueos
• 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 Cartuchos), 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 La Rata Sagaz, the reward room has eight pedestals with Corazóns, Armadura, Llaves, Fogueos, Piedra de guon de cristal, and Munición
• Four special chests in the room require Llave de la ratas and contain Elimminental, Queso comido en parte, Saca sagaz, and Botas de rata. Llave de la ratas 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 Llave de la rata is needed to feed it
• Feed the snake 4 guns or items and it follows you as a companion until the Armadragón fight, where it defects and is absorbed to trigger the Advanced Dragun. That is the route to Grial hueco and the "Advanced Slayer" achievement (the other is throwing a Huevo raro into fire)
• The snake refuses Televisor estropeado, Esponja, and Ganzúas fiables — do not count on those to make up the four
• Alternatively, you can kick the La Rata Sagaz into the snake to feed it
• After the reward room you can proceed to the Hollow normally, or spend a Llave de la rata to skip directly to the Forja
• First visit unlocks Huevo raro

R&G Dept.

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

Cost: 1 Munición maestra + 2 guns or items (sold to the Comprador siniestro in Hollow)

Steps to enter

1. Find the Comprador siniestro in Hollow
2. Sell the Munición maestra and 2 items — the entrance opens immediately after the third item is sold, so sell the Munición maestra last if you want to keep trading first

Notes

• The cost is steep: a Munición maestra 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 Armanim there is no exit elevator — you have to throw yourself off the rooftop arena to reach the Forja
• 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