A little over a year after releasing his “Nostalgia, Ultra” mixtape, which included a creative cover of Coldplay’s “Strawberry Swing,” Frank Ocean will be gallivanting around Europe with the U.K. arena rockers later this summer. The R&B newcomer will join Coldplay (as well as fellow openers Marina & The Diamonds) on 10 dates beginning Aug. 28 in Copenhagen. Swedish pop veteran Robyn, Irish alt-rockers Ash and Roc Nation singer Rita Ora have also been announced as openers for Coldplay’s European tour, which kicks off May 18.