Complex sentence: His original intentions were pure and beneficial, he devoted most of his life finding ways to protect Corneria, however his work had convinced him that the only way for his planet to be protected was if he was to be the sole ruler.
Split into simpler sentences: His original intentions were pure and beneficial, he devoted most of his life finding ways to protect Corneria. However, his work had convinced him that the only way for his planet to be protected was if he was to be the sole ruler.