Complex sentence: Triple H then claimed to have a "Plan B" which, later that night, was revealed to be Rollins attacking Ambrose and Reigns with a steel chair and rejoining The Authority, turning heel once again.
Split into simpler sentences: Triple H then claimed to have a "Plan B" which proved to be true. Later that night, Rollins attacked Ambrose and Reigns with a steel chair and subsequently re-joining the The Authority, turning heel once again.