Shutdown

The battlefield becomes subject to the Pitch
Black rules, see p.120 of the Necromunda
Rulebook. All terrain pieces become inert and
generate no additional effects beyond those laid
out in the core rules (i.e. counting as impassable,
blocking line of sight, being climbable, etc.).
All doors seal and cannot be opened normally
(see p.52 of the Necromunda Rulebook),
but may still be forced.
Discard on a 4+