Complex sentence: Talion helps Ratbag ascend the ranks to the level of warchief by killing each of his immediate superiors so Ratbag can take their position, while also assisting Hirgon in saving outcasts who have been enslaved by Sauron's forces, including Hirgon's wife Eryn.
Split into simpler sentences: Talion helps Ratbag ascend the ranks to the level of warchief by killing each of his immediate superiors so Ratbag can take their position. He also helps Hirgon to save outcasts enslaved by Sauron's forces, including Hirgon's wife Eryn.