Complex sentence: Learning that Al became a vessel for the Philosopher's Stone, he deceived the boy by offering to teach him how to master the Stone, but in reality, he used Al to create a fake soul to imprint his memories of her onto.
Split into simpler sentences: Learning that Al became a vessel for the Philosopher's Stone, he deceived the boy by offering to teach him how to master the Stone. But in reality, used Al to create a fake soul to imprint his memories of her onto.