Complex sentence: Having succeeded the trial, Origin grants the party's request to destroy all parallel worlds, but with Elle's transformation into a divergence catalyst nearly completed, Ludger saves her by becoming a divergence catalyst before her, sacrificing himself in her place.
Split into simpler sentences: Having succeeded the trial, Origin grants the party's request to destroy all parallel worlds; however, Elle will also disappear as she has nearly completed her transformation into a divergence catalyst. Instead, Ludger saves her by becoming a divergence catalyst in her place.