From the Organized Play website: Pokémon Organized Play Seasonal Format Change Effective: 9/1/2008 In the interest of maintaining a healthy tournament environment, Pokémon Organized Play removes older sets from the Modified format at the beginning of each new tournament season. Each rotation challenges existing players to create new strategies while allowing new players to get into organized play with a minimum investment. The following Pokémon TCG sets will be removed from the Modified format for the 2008–2009 tournament season: EX Holon Phantoms EX Crystal Guardians EX Dragon Frontiers EX Power Keepers POP Series 4 Promo Cards POP Series 5 Promo Cards All Black Star Promo Cards numbered 037-040 As this change does not take effect until the end of the current tournament season, the sets listed above will continue to be tournament legal through the 2008 Pokémon TCG World Championships. New sets will become tournament legal when they are released, per the Pokémon Organized Play Tournament Rules. http://www.go-pokemon.com/op/tournaments/docs/2008-2009/modified_format_08_09.pdf Kind of duh, but nice to know for sure.