Astrolab

The Astrolab is a special level accessible after the Throne Room only when playing with 5 Boss Stem Cells active.

The Astrolab is the main laboratory used by the Alchemist for his experiments with curing the Malaise. This biome is particular in that it consists of a succession of floating platforms and structures with ladders connecting them, which the Beheaded must climb to reach the exit leading to the Observatory. If the player falls in the gap between platforms, they drop down far below and take a lot of damage thanks to the extreme enemy level scaling in this biome.

On the walls of the Astrolab rooms, one can see scientific drawings and schemes alluding to the Alchemist's experiments with the Malaise and Cells, as well as plans to brew the Panacea.

In order to reach the exit, the Beheaded needs to collect a series of keys by beating Elite enemies. An Elite Failed Experiment and an Elite Slammer drop the Elevator and Allen keys, respectively, which can be used to reach a room where two Elite Slammers are waiting. Upon defeating them, the player finds two Guardian's keys, which open the doors to the Observatory.

Access and exit
The Astrolab can only be accessed from the Throne Room when playing with 5 BSC active. Its only exit leads to the Observatory.

Scrolls
The Astrolab contains 2 Dual-stat scrolls.

Enemy tier and gear level scaling
In the table below, you will find the gear level and enemy tier of the Astrolab based on difficulty. Even though the Astrolab can only be accessed on Hell difficulty there are enemy tiers set for lower difficulties.

Chests and loot

 * 1 Treasure chest

Shops

 * 1 Weapon Shop
 * 1 Food Shop

Exclusive blueprints
The Astrolab is home to two unique enemies that cannot be found in any other location of the island: the Magistrate of Death and the Defender. Those two enemies carry exclusive blueprints, respectively for the Hemorrhage and the Thunder Shield. In addition, a hidden tower located under a corridor contains the Apex Key behind a series of traps, which can be used to retrieve the blueprint for the Sonic Carbine (see Gallery).

Enemies
In addition to the unique enemies Defenders, Magistrates of Death, and Librarians, the Astrolab is home to Failed Experiments, Slammers and Bombers.

The table below lists which enemies are present in the Astrolab and which blueprints each may drop.

Crow experiment room
A room filled with empty crow cages hanging from the ceiling and a broken vat with a tap and a half filled filled flask standing beneath it. There is a desk with a grimoire of the Alchemist. This room is likely the explanation behind the existence of Slammers.

Research notebook
"Against all odds, this solution created mutations in the infected crows instead of curing them."

"Some subjects managed to escape by breaking the bars of their cage!"

"God only knows where they are now... I hope their condition has stabilized now."

Solution
When examined the beheaded notes:

"Another failed cure..."

"How many crows drank this solution?"

Cage
When examined the beheaded notes:

"All these broken cages..."

"Those crows give me the creeps!"

Trivia

 * Although not through normal gameplay, it would be possible to access the Astrolab with 4-0 BSC active: the level is present in the .json files for all the difficulties.