Have a monthly fee for the premium league. Create a system where you roll the game between expansions for 3-6 months? at the time so we can have periods with vanilla Pox(wich was great) aswell as periods with the game as in the current state, and expansions in between. The premiums get to play the league wich will be expansion related, if the league is from Rise of Serkan then runes up to that expansion is the ones used. The free to plays get to play custom games as the game is now with all expansions. Have a premium ladder for the current ongoing league and have a free to play custom game ladder, wich resets with the premiums. Make Limiteds runes for each factions that are related to the ongoing expansion but put the overall rune numbers relative fixed from here on. So you can make Limiteds great again aswell. So the next chance to get a limited from that expansion, would be when it comes back in the league loop.