Complex sentence: On the February 21,2011 episode of "Raw", Triple H returned to WWE by interrupting the return of The Undertaker and challenging him to a match at WrestleMania XXVII, which later became a No Holds Barred match.
Split into simpler sentences: On the February 21,2011, "Raw", Triple H returned to WWE by interrupting the return of The Undertaker. He challenged him to a match at WrestleMania XXVII, which later became a No Holds Barred match.