First of all I am loving the new add-ons. If you could add some arena 2v2 modes or create a type of guild group where people could do clan wars and other organized events that would really bring a advantage to the game. Clans should be able to trade cards, 1v1, participate against other clans to determined who is the strongest fear.
Some classic modes where people could earn certain packs would be nice. Maybe 1 or twice a month? On a specific day of the week with a announcement so everyone will understand when each classic challenge is taking place