Complex sentence: Overwhelmed by the cheering crowd outside, Arthur calls out to Merlin for help, who returns from Bermuda (and the 20th century) and is elated to find that Arthur is the king that he saw in the future.
Split into simpler sentences: Overwhelmed by the cheering crowd outside, Arthur calls out to Merlin for help. Merlin returns from Bermuda (and the 20th century) and is elated to find that Arthur is the king that he saw in the future.