In Hades (2020) by Supergiant Games, each biome counts as one stage in a run. There are four main biomes (regions) you fight through to reach the surface:

The 4 Biomes / Stages in a Standard Run

  1. Tartarus – The first biome; prison-like, with skeletons and basic enemies. Boss: Megaera (or sometimes Theseus/Asterius in later patches/mods).
  2. Asphodel – Lava-filled second biome with tougher foes. Boss: Learned Boss (varies; often Theseus & Asterius).
  3. Elysium – Third biome; more open, elite enemies, and challenging rooms.
  4. Temple of Styx – Fourth and final biome before the final boss. Leads directly into the last encounter.

So, for your question:

“How many stages in 1 biome on Hades?”

Technically, one biome = one stage. You don’t subdivide a biome into multiple stages during a single attempt. Each biome is treated as a single continuous region made up of multiple rooms, but the game counts it as one cohesive stage toward your escape.

TL;DR

  • 1 biome = 1 stage
  • Total biomes/stages in a full escape attempt: 4 (Tartarus → Asphodel → Elysium → Temple of Styx)

Information gathered from public forums or data available on the internet and portrayed here.