Complex sentence: Radiohead began a world tour in May 2016, with dates in Europe, North America, and Japan, joined by additional drummer Clive Deamer, who also performed with the band on the "King of Limbs" tour.
Split into simpler sentences: Radiohead began a world tour in May 2016, with dates in Europe, North America, and Japan. They are joined by additional drummer Clive Deamer, who also performed with the band on the "King of Limbs" tour.