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I've played through the complete campaign, the revenge campaign, beat all but one challenges, unlocked all cards for two decks but still there are decks such as "Mind Maze" that I cannot play with.
How do I unlock those?
To unlock those decks, go to any campaign map, and click on the icon on the bottom right to go to a menu where you can unlock and fight various planeswalkers. Each of them uses a pretty good deck, including mind maze.
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