A translucent indestructible bubble that shields racers from a heat's toxic air — and a new rule letting the vehicle-less still win.
The survival containment is a race rule introduced for the tenth floor's Heat Four, announced by the coerced loudspeaker voice of Zev. A translucent, indestructible circular bubble spreads about a meter around each vehicle or mount, protecting racers from the toxic, unbreathable air of the jungle track; spells and projectiles pass freely through it. Every containment heat requires a two-hour pit stop (garage access for repairs) and features vendors selling air countermeasures.
Crucially, it changes the losing condition: if a vehicle is destroyed or a mount killed, the team no longer automatically loses — instead they lose their containment, and if they can somehow survive the poison air and still cross the finish line before another team, they live (though they don't get their conveyance back). Last place still loses. This heat also introduces the winner's key (opening one defeated team's garage for supplies or a whole spare vehicle) and has multiple heats sharing the track, with containment-stealing disabled.
A translucent, barely-visible spherical bubble, catching the light like soap film, enveloping each racing vehicle or mount.
A toxic-air survival shield and rule-change mechanic governing the jungle heats.