How the mines are laid out
The mines are divided into biomes, each starting at a fixed floor and running until the next begins. A biome sets what ore and gem appear, which artifacts can be dug up, what armour is themed to it, and how much combat experience its monsters give.
Floors are generated fresh each run, so nothing about a specific floor's layout is memorisable. What is stable is the biome: at a given depth you always know which materials are on the table.
The creature table lists a kind once for each version of it, with the biome that version spawns in. The game names its tougher versions no differently — they are the same creature met further down — so a repeated name with more health is exactly that, and the biome column says how far down. Three creatures are listed in no biome at all: one is spawned by another creature rather than by the floor, and two are defined but referenced nowhere, so they carry a dash rather than a guess. Drops split two ways: the ones listed plainly each roll on their own, while those under at most one of compete for a single slot — one of them at most falls per kill, which is why their percentages are written as ceilings. Each area also names an artifact set, shown on its card: digging at a given depth is progress on one specific museum case rather than on the wing at large.