Complex sentence: Mullins left the series after the first season and was replaced by Casper Van Dien for season 2, in which it was revealed that Cage refused Shang Tsung's offer to fight for Outworld, but was reluctantly recruited by Raiden to participate in the tournament.
Split into simpler sentences: Mullins left the series after the first season and was replaced by Casper Van Dien in season 2. During the events of Season 2, it is revealed that Cage refused Shang Tsung's offer to fight for Outworld but is reluctantly recruited by Raiden to participate in the tournament.