Complex sentence: Optimus pleads Dinobot to escape with them, but he refuses and bids them farewell before being engulfed in an explosion as the "Nemesis" returns to the ocean.
Split into simpler sentences: Optimus pleads Dinobot to escape with them, but he refuses. Dinobot then bids farewell to Optimus, and is shortly engulfed in an explosion as the "Nemesis" returns to the ocean.