Has anyone ever tried creating a variant sort of like D&D? Archenemy or Planechase is close I think (never actually played either, so you can tell me if I'm right or not), but not quite, I was thinking more along the lines of a game where one person builds a deck with cards specifically to influence the game that the other players have to deal with, or that has group hug mechanics, but they can't attack or be attacked. Creatures can be used by the GM, but only for their activated or static abilities, such as Phelddagrif for example, so they would essentially be treated like enchantments or artifacts like in Theros or Mirrodin block regardless of whether they're actually that type officially. Maybe using dice rolls or spells could remove them, and the other players use their decks to defend themselves while they fight in sort of arena style combat. I haven't quite figured out exactly how it would work, but I'm open to suggestions.

Yes, somewhere else in the Flavor and Storylines section of the forum is a thread with a link to a whole system that sort of uses Archenemy mixed with RPG character building to influence player deck construction. When I'm at a real computer and not my phone, I'll see if I can't find it for you and post the link.

EDIT: Found the link......sorta. So it turns out the link I had was pointing back to the old Wizards forums (which are now gone). I still have the PDF document if you want it after scrolling through the thread I was writing about it.

Heh, I didn't get a notification so I replied before I saw your edit lol. Sucks that the PDF doesn't exist anymore, but it's a cool idea.