They can't
Rather than taking their form based on their holders Deck, they take a form relative to the legend that is described
I wish I could be diving into dungeons, either in a silly or serious storyplaying with cards that upgraded as I used them across matches, or ridiculous new takes on Power that could never be printed, or with cool enchantments starting on the battlefield
In other environments, it presents a frustrating roadblock against aggressive decks
It has been featured in subsequent game remakes and spin-offs, maintaining a presence that ensures new generations of players are introduced to its capabilities
For every Tree of Redemption or Akroma you open, you'll also get a Jace, the Mind Sculptor and an Imperial Recruiter sooner or later, and it all works out in the end