Complex sentence: Kai returns during the Omniverse in "An American Benwolf" in London to help her grandfather, with support of Ben and Rook Blonko, to keep the Chadwick and the Forever Knights from obtaining Excalibur.
Split into simpler sentences: Kai returns during the Omniverse in "An American Benwolf". She comes to London to help her grandfather (with support from Ben and Rook Blonko) to keep the Chadwick and the Forever Knights from obtaining Excalibur.