Complex sentence: The net is being made so that a spoiled, dark Princess can steal Spectra "the ultimate jewel in the universe" for herself, and tow it back to her world with her massive spaceship.
Split into simpler sentences: The net is being made so that a spoiled Dark Princess can steal Spectra "the ultimate jewel in the universe" for herself. The Princess inevitably plans to tow the netted Spectra back to her world with her massive spaceship.