During the last test, Chell has to stand on a moving platform. At the end of the platform's track, it will carry her into a fire pit. GLaDOS thanks Chell for doing the tests. At the last minute, Chell uses her Portal Gun to escape the trap. While trying to escape the building, Chell is led into a room where she finds GLaDOS. Chell breaks a white ball that fell out of GLaDOS. GLaDOS tells her she was stupid to break it because they did not know what it was, but GLaDOS quickly figures out it was her morality core. She tells Chell the people who worked for Aperture Science installed it to make her stop killing them with "Deadly Neuro-Toxin". Because Chell broke it, GLaDOS can use the Neuro-Toxin again. Chell has a time limit of 6 minutes to kill GLaDOS before the Neuro-Toxin kills Chell. After breaking pieces off of her and burning them, GLaDOS is destroyed and Chell escapes the building. 