Its inevitably a bit of fudge but that is half the fun of a crossover What powers your deck in Magic: The Gathering are Land cards, and this includes some stunning examples of terrain from the 40K universe, such as Crumbling Necropolis, Arcane Sanctum (home to the Emperor), and Choked Estuary
However, there are no color restrictions, so you can play cards of other colors, or no colors (such as lands)
Local card shops are also fantastic, as you can often see the cards in person and truly appreciate the artwork up close before making a purchase
Spell Cards are unique cards that can be triggered during Duels, oftentimes providing bonuses to the controlling player of a card
If you already know TCGs and you've played some, then I totally recommend the single-player decks
(NOTE: This would be illegal in the real game, since an attack cannot be declared on the first turn