If you know the game then I need your input. I have only seen a handful of cakes on the internet. All similar versions of a deck of cards. Anyone a fan? What else could be made into a cake and be really cool to a huge Magic fan?
The only thing I can think of that wouldn't involve making the cards would be to incorporate the different symbols somehow. Perhaps make different cookies with the plains, swamp, etc.
If you're good at modeling perhaps a model of a planeswalker?
But I think since the art for magic is so detailed, it would be very difficult to make a cake that wasn't just the cards without using edible images (which can be another thought)!
I've not looked at a deck for years, if they have a favoured card and you are into carved cakes then you might consider a simplified 3D of the main creature/symbol on the card.