The Laboratory Rupture is another form of Rupture encountered in the Military Outpost's weapon laboratory, it also served as the third boss of the game.
Blake enters the Military Outpost's weapon laboratory in order to retrieve a key card in order to use the elevator to reach the surface. However shortly after he entered the lab, the large Rupture emerges from the lab's ceiling and it along with a Walker attacked Blake, Blake was able to kill it by shooting it several times and finally burning it.
When you enter the lab door a little cutscene will introduce you to the third thing boss, this is the hardest boss in the game byfar if you don't know the proper technique to kill it, inside this same room is a Walker held in a glass container besides the boss. Here is the trick to beating this boss, when you enter the room run straight, don't even move a little bit, stand right at the face of the boss, so close that it wouldn't be able to hit you, if you manage to do this then you are in a really nice place, from here you can shoot the boss until its red , and then you should blow the tank of the Walker and try to kill it, but remember , don't leave that place where you are standing or else the boss will get you. Try to kill the Walker from the same place where you are. If he comes close to you use the flamethrower of if it stays away then the only thing to do is to throw a flame grenade. When the Walker is dead its time to kill the main boss. To kill the boss throw a flame grenade right underneath it and run quickly back , keep on retreating back so that the grenade doesnt affect you, if the boss doesn't die in the first grenade then the second should definetly kill him. When it is dead then a new objective will be added to your list which is escape.