PS: Something you might not be aware of, we in the Card Idea and Art section can playtest cards before they are added to the trainer. (Few people actually do it but the option exists.)
In the Card Idea and Art section we have adopted Sync.in as a useful editable online document source. http://sync.in/CardIdeaPlanning is the hub. You should be able to find your way from their to our CardIdeaBattle. http://sync.in/CardIdeaBattlefield1 is an example battle field. Each playtester puts their deck below and uses a specific RNG to order their draws. Each turn they check what they drew and edit the game data as they play cards/attack. Since humans are in complete control, we can simulate effects that are not coded into the trainer yet.