How close to the card game are you thinking? Are you planning to actually use Magic Cards in the game somehow?
If you're using it as a setting, I would just call it Fantasy and add a rule that the cards effects exist in this setting. If you see something on a card, it's plausible here.
If you want to get more detailed (but further away from the gameplay of MTG) consider making the colors into something like approaches from Fate Accelerated. So there are five colors, right? have each player make one color a 3 point color, one a two point color, one a one point color, and the remaining two are zeroes. Then let them spend a fate point on that bonus when they can justify an action, spell, stunt or anything by it's color, either by displaying a card with the color and effect, or doing something in the spirit of that color (ie, if they do something deceptive, they can add their blue bonus).
you can make the actual spells from the cards into stunts easily enough, I think.
I have never thought of MTG as a setting, so i don't think i have enough details about what you're hoping to accomplish.
"It is easier to outsmart people than to outdumb them" - Scott Meyer (as Omnipresent Man)