| A. South Breach Door | Starting position; reinforced frame provides standard cover. | The door seals when combat begins. It cannot be reopened before the purge. |
| B. Central Transfer Lane | Open 15-foot-wide lane with little cover. | Floating debris enters the lane after the gravity flare, creating two squares of difficult terrain each round. |
| C. Guard Stations | Waist-high consoles provide standard cover. | A creature adjacent to a console can attempt purge-delay or evidence-download actions. |
| D. Upper Gantry | 10 feet above the floor; railings provide lesser cover. | DC 15 Athletics check to Climb without the ladder; a critical failure causes a 10-foot fall. |
| E. Containment Vault | Frosted chamber behind thick transparent panels. | The twins begin here. The panels become broken terrain after the first gravity pulse. |
| F. Maintenance Hatch | Northwest floor hatch, sealed by two independent locks. | Two successful override actions open it. The hatch leads to a 20-foot service drop. |
| G. Evidence Terminal | Exposed terminal beside the vault. | A successful download provides proof of illegal experimentation but costs actions during the countdown. |