Ossuary

The Ossuary is a third level biome.

There's a point where even mass graves won't work to fit all the bodies. No, after the night of the bloody riots, they knew that they could not afford to dig massive holes. Instead, an entire section of the prison was decided to be the perfect place to host them. Then it was set ablaze, and the ashes spurted out. Bones and flesh now litter the floor, and bodies that are barely even recognizable as human litter the grounds. However, with so many bodies, even fire was not fast enough. Before it all could be burnt down, the bodies began to awaken, and the flesh started to move.

Access and exit
The Ossuary can be accessed from either the Promenade of the Condemned, or Prison Depths. In the first case, it requires having the Teleportation rune, while in the second the Spider rune is required.

The only exit out of the Ossuary leads to the Black Bridge, where the Concierge boss awaits.

Ram rune
A Slasher elite can be found here who drops the Ram rune. It disappears after being defeated once.

Scrolls
The Ossuary contains 4 scrolls, including 2 Power Scrolls and 2 Dual-stat scrolls, which cannot spawn in areas requiring the Teleport, Ram or Spider runes. When 3 BSC are active, this biome has 2 guaranteed Scroll Fragments, and when 4/5 BSC are active, this biome has 3 guaranteed Scroll Fragments.

Enemy tier and gear level scaling
In the table below, you will find the gear level and enemy tier of the Ossuary based on difficulty.

Boss Stem Cells rewards

 * 1 BSC: Food shop
 * 2 BSC: Treasure chest

Chests and loot

 * One guaranteed cursed chest spawn in the level.
 * Another cursed chest can spawn in the level (10% chance).
 * One item behind spider rune
 * One item behind homunculus rune
 * One elite room

Shops

 * There is a food shop behind the 1 BSC door.
 * Weapon shop.

Exclusive blueprints
The blueprint for the Marksman's Bow is found behind the 8 minute timed door located in the Collector transition area before the Ossuary (only found when entering from the Promenade). The blueprint for the mutation Extended Healing can be found in a secret area within the level.

The blueprint for the melee weapon Torch is looted from Spawners, which are found exclusively in this biome. The Ossuary is also the only place where one can get the Cloud Outfit, which drops from Shockers with 3+ BSC active.

Enemies
In the Ossuary, you will find two unique enemies, Thornies and Spawners. Shockers are another iconic enemy of this level, along with Slashers and Lacerators. On higher difficulties, the Zombies are replaced by Dark Trackers, Bombers and Failed Experiments.

In the table below, you will find which enemies are present in the Ossuary depending on difficulty level. For each enemy, any common, uncommon, rare or legendary blueprints they carry are indicated. When applicable, the minimum difficulty level for blueprint acquisition is specified in brackets.

Alchemist Grimoires
Main Article: The Alchemist

In the Ossuary, the Alchemist was applying the substance found in the walls of the Slumbering Sanctuary on bones from corpses, likely executed prisoners. The substance's effects were unpredictable and the Alchemist reflects whether his experiments are worth killing so many people.