Complex sentence: Their imperial machinations lead them to turn their cloned Zentraedi miners into a formidable military force, used to steal the Flower of Life from the Invid, defoliate Optera and conquer the Local Group of star systems.
Split into simpler sentences: Their imperial machinations lead them to turn their cloned Zentraedi miners into a formidable military force. The Zentradi proceed to steal the Flower of Life from the Invid, and conquer the Local Group of star systems.