Passage

The Passages are the areas where the player will find themselves when going in between areas. A passage will usually take the appearance of the biome it leads to. In every passage the player will find:
 * The Collector, who will take blueprints and cells to unlock Weapons, Skills, Mutations, Permanent Upgrades, and Outfits.
 * The Blacksmith's Apprentice, who will reforge the modifiers and upgrade your gear for gold.
 * Guillain who will give you Mutations to assist on your run.

In the passages after boss biomes (Black Bridge, Insufferable Crypt, Nest, Clock Room and Guardian's Haven) the player will find the Legendary Forge where they can give cells to the Blacksmith for permanent upgrades to the quality of gear found during runs.