after purchasing maps, the Multiplayer is suppose to sort out everyone who has the maps, on the playlist you are playing. After purchase i still have yet to be able to play them on Invasion playlist setting(http://www.bungie.net/stats/reach/playlists.aspx) "Tempest" is a map selection. i have yet to encounter this map here, and on Big Team Slayer. maps are only being playable on the DLC playlist