Dark Energy Reactor

The Citadel's dark fusion reactor is the combine's main source of power and destruction in City 17. The reactor powers the majority of the citadel's energy and entanglement devices preventing escape by any citizens outside the city poundrys. The Dark Fusion reactor is destroyed by Gordon Freeman at the very end of Half life 2, as he attempts to stop Dr.Wallace.Breen's escape. In destoying the reactor, it causes the tip of the citadel to explode and corode until the inevertable energy explosion that hits Gordon and Alyx's train at the end of Episode 1. This huge energy blast was powerful enough to force a information packet off to the combine overworld. After the packet is thrown off world, huge portal storms, which were originally caused by the Ninilith's downfall, began to start up again. Issac Kleiner, Eli Vance and Arne Magnusson must then finish his missile in 'White Forest' to finish the huge portal storms and prevent another combine invasion.

Portal storms carry huge amounts of Portal Energy which eventually gather and become large enough to rip open a dimensional portal spanning to the combine overworld.

The Portal storms resemble huge blue like rays shooting out from the citadel, eventually stretching out into a huge light blue portal. Dr.Breen was apparently killed in the fusion reactor explosion but his true fate still remains unknown...