This. I hate dropping cash on cards that end up going into a trade binder or box and never see the light of day again. "Oh, that sounds like a great idea," has come out of my mouth so many times, and been so very wrong even more. It was a great tool for testing, regardless of if you were eventually getting the card onPeople have said the magic words: play test. If MTGO offered a way to playtest decks you have yet to buy, there would be no need for software like this. Using a land that says "JTMS" in sharpie before actually spending cash on the card is common practice in paper Magic. Digital Magic needs something like this, and MWS, 'trice, OCTGN and the like have filled that gap that's been left open so far in MODO.
MTGO or in real life.