Mine Cells — Reference
Cells and the Cell Crafter
Cells are the currency the whole progression runs on. They drop from kills and are spent at the Cell Crafter, a workstation you place in your own base rather than inside the dimensions.
The Cell Crafter's interface lists what you can currently make and what it costs. Recipes unlock as you go, so the list grows with the runs you have survived rather than being open from the start.
What comes out of it is the armoury from the source game - the Assassin's Dagger for coming in from behind, the Heavy Crossbow for holding a corridor, along with swords, bows and shields - plus the runes that open the next doorway.