In case you weren't around for previous remaster sets like Kaladesh Remastered, they're basically selected cards from all the sets in the block (for this case that would be Shadows Over Innistrad and Eldritch Moon), combined into one draftable booster product. There will likely be drafts or you can just buy the packs from the store or craft the cards with wildcards etc. For Amonkhet Remastered, they also included some reprints from sets outside of the block, but with new flavor/art to match the plane, so that might happen here as well. We don't expect new cards that aren't reprints