Loki had still let the Chitauri's alien army through the wormhole.
Tony was the first to realize it. The moment he understood that an arrogant bastard like Loki would want everyone watching his grand performance, he thought of Stark Tower, one of New York's landmarks.
His home stood high above the city, and the reactor powering the entire tower could also provide the energy needed to activate the Tesseract. There was simply no more perfect testing ground than Stark Tower.
"Damn it!"
He told Steve his theory, leaving Captain America to assemble the others while he flew ahead to New York.
He spotted Loki as soon as he reached his doorstep.
"Sir, I have shut down the Arc Reactor, but that device is already sustaining its own power supply."
JARVIS warned him.
Tony knew what his AI butler meant. It was the Spatial Reaction Device Dr. Selvig had built for Loki.
He tried to disrupt the device with a high-temperature beam, but failed.
"That barrier is pure energy."
The blue shield the Tesseract had formed around the device reflected Tony's entire attack straight back at him.
Then something even more troubling happened.
With blue eyes wide, Selvig frantically told him that once the device started running, there was no way to stop it.
He was still under Loki's spell. The aliens invading Earth like a swarm of locusts left him completely unmoved; instead, he excitedly showed Tony the fruits of his work.
The war had begun. If he could not stop it, his only choice was to fight to the end.
Without another moment's hesitation, Tony flew into the sky. His armor switched to combat mode, and he fired missiles at the Chitauri.
Bang! Bang!
The black smoke and flames from the explosions stood out sharply against the clear sky.