Complex sentence: Ross was supposed to humiliate Stonebanks after he became both a traitor and a bloodthirsty nefarious gun runner, but Stonebanks was successful in staying alive and has now made it his mission to assassinate The Expendables.
Split into simpler sentences: Ross was supposed to humiliate Stonebanks after he became both a traitor and a bloodthirsty nefarious gun runner. But Stonebanks was successful in staying alive and has now made it his mission to assassinate The Expendables.