Xiao Xie had no interest in Thor's Hammer. It was merely a divine artifact! What he cared more about was Thor's destiny, the Mind Stone in Loki's possession, and the Cosmic Cube.
In the Marvel Cinematic Universe, the "Infinity Stones" were entities that had existed before the birth of the universe. After the Big Bang, these entities transformed into six Infinity Stones, each representing a fundamental aspect of the universe.
Inside the Cosmic Cube was actually the Space Stone, one of the six Infinity Stones. The Space Stone allowed its user to instantly move themselves or any objects to any location in space. It could also warp or rearrange space at will.
Xiao Xie knew that the Cosmic Cube should currently be in S.H.I.E.L.D.'s possession, but it was not yet time for him to act. He wanted to wait until Loki used the Cosmic Cube to open a spatial portal and release the Chitauri army onto Earth. Then, he would appear as Uchiha Madara, save the Earth, and naturally seize the Cosmic Cube.
The Mind Stone allowed its user to enter the minds of others, and it could also bring all dreams, thoughts, and ideas into the user's mind. It enhanced mental strength and increased psychic abilities.
The Mind Stone was currently in Loki's hands—the gem on the scepter he carried. When the time came, Xiao Xie would seize both the Cosmic Cube and the Mind Stone.
Thor had been banished to Earth by Odin and lost all his Divine Power. Moreover, if he failed to change his impulsive and arrogant nature, then even if he found Thor's Hammer, he still would not be able to lift it.
However, Thor had not gained nothing. Although he had lost all his Divine Power on Earth, he had begun to integrate