You may have seen this already on the Grand Melee League page, but the club meeting on June 17 is the Planechase round for the league.
What does this mean? There are no special deck building rules, however there will be a shared deck of planes used at the table. Check out a Wizards article on Planechase for the basics. In the melee game, the Planes will move around the table with the active player. On your turn, the planes will be in front of you, and you can roll the planar die or not as you wish. Any effects from moving to or from planes will affect only those players in your range. When your turn ends you pass the shared deck and the planar die to the next player.
Shared Plane decks will be provided for the first two tables only. If there is a third table, this will be a normal melee round with no planes.
Get ready for some mayhem!