What is the point of the Oubliette in Enter The Gungeon?
The Oubliette is a secret floor in Enter the Gungeon that, when completed, will give you an entire floor’s worth of rewards in the form of Shells, room drops, Shops, Chests, and Boss rewards.
In addition, you can get the Old Crest from the Oubliette, which is necessary to unlock the second secret floor, Abbey of the True Gun.
You can access the Oubliette through a secret trapdoor in the Keep of the Lead Lord. The floor will look like a sewer littered with toxic waste, trash bags, and dying Bullet Kin.
To access the room with a hatch that leads to the Oubliette, you have to find items to extinguish the fire at the Fireplace in the Keep of the Lead Lord. You can typically find a few water barrels in a separate room on the same floor. If you can’t find water barrels, any non-oil Goop will work as well. Another neat trick to get to the Oubliette trapdoor room without using water barrels or Goop is by using the Teleporter Prototype.
After extinguishing the fireplace and activating it the first time, the chance for water barrels to spawn in the same room as the Fireplace will increase significantly, making it easier for you to access the Oubliette in subsequent runs. It also unlocks the Trashcannon and the Grate Hall achievement in-game.
Lastly, you’re going to need at least two keys – to open the Fireplace trapdoor and to enter the trapdoor that leads to the Oubliette proper.
The Oubliette will be a very challenging chamber in Enter the Gungeon full of powered-up enemies such as Mutant and Veteran Shotgun Kin. Despite being one of the first floors in the game, the Oubliette will have a jump in difficulty that can be quite shocking for new and veteran players alike, as Enter the Gungeon is known for its relatively linear difficulty spike through each of its floors. (In terms of difficulty, the Oubliette will be at the difficulty of floor three.)
However, if you have the skills and the know-how, clearing the Oubliette will get you a decent number of Shells, keys, Blanks, armor, chests, and a Boss reward for defeating the Oubliette boss, Blobulord.
Lastly, completing the Oubliette secret floor will get you the Old Crest, which is a necessary passive item to unlock the second secret floor in the Gungeon, Abbey of the True Gun.
The Oubliette secret floor will give you a unique challenge that will reward you with the appropriate loot for your efforts. You can also use this secret room as a pseudo-training ground to hone your ability to dodge bullets and use effective movement to avoid taking damage on subsequent floors in the Gungeon.