The Red Door is an environmental hazard found in missions.
Red Doors are illuminated, red doors with a distinctive white eye symbol. These doors exist throughout Redacre and is way the Shape spawns and traverses around the map. Although they're called Red Doors, they also exist as hatches on the ground. Red doors and hatches are found on the surface and in almost every room and area in the Maze. Sleepers, Lucids, and the Stalker can use Red Doors to travel.
The Blackout Club
There is no way to "disarm" or avoid Red Doors. They exist throughout the map and allow the Shape to traverse quickly to the location of disruptions and disturbances caused by players. Generally, it's good to be aware of where the Red Doors are and places where the doors are less condensed, especially when targeted by the Shape. One way to guard against the Shape coming out of a Red Door is to put a Sleep Tripwire in front of it, though there's a chance that a Sleeper or Lucid may trip the trap instead. This is also a method to catch Stalkers coming out of a door.
Standing near or on the door will cause the player to see bright flashes and a warning to stay away from the Red Doors.
The Stalker can use Red Doors as a fast mode of transportation around the map. It is especially useful when trying to catch up to The Blackout Club members and to record their actions. The Stalker, however, cannot stay behind Red Doors indefinitely, and must wait 30 seconds before traveling through another Red Door.