Complex sentence: They realize that Galvatron is plotting to use the Seed and the K.S.I. drones to conquer the world, by detonating the Seed in Hong Kong, as K.S.I. has brought it there to use it in the remote Mongolian desert to create vast amounts of usable Transformium.
Split into simpler sentences: They realize that Galvatron is plotting to use the Seed and the K.S.I. drones to conquer the world, by detonating the Seed in Hong Kong. K.S.I. plans to use the Seed in the remote Mongolian desert to create vast amounts of usable Transformium.