Mixing classes is easily the best part here. Swap one class for another and a familiar card can suddenly serve a completely different purpose. With a collection this large, stumbling onto your own peculiar build feels better than blindly copying a preset deck. Free shop purchases are already unlocked in the current version, which makes filling out the collection much easier.
There is more than the usual PvE loop, with an arena and Roguelike mode available when you want a change of pace. The 40-plus bosses also have enough bite to make you rethink a deck, especially when an enemy exposes a weakness you did not notice before.