Complex sentence: Celestia, using the mystical "Elements of Harmony", banished her sister to the Moon for one-thousand years, therefore becoming the sole princess of Equestria for nine and a half centuries until Princess Cadence would ascend to become a ruling alicorn princess alongside Celestia.
Split into simpler sentences: Celestia, using the mystical "Elements of Harmony", banished her sister to the Moon for one-thousand years. Therefore, becoming the sole princess of Equestria for nine and a half centuries until Princess Cadence would ascend to become a ruling alicorn princess alongside Celestia.