How'd you do an MTG anime?
What studio would you pick? What sort of storyline would you like?
I'd probably say ufotable since they proved they can do magic fights through Fate. Planeswalkers would be somewhat of a mixing between servants and magi fights.
As for story arc, I think the Zendikar arc would be good for a long-running story. Going all the way through to Oath of the Gatewatch would probably take multiple seasons though.
So long as the protagonist plays Permission Blue.
Make it about the actual game. Guy buys an intro deck and tries to play at his local store, gets trashed and decides to gitgud to show them all. Focus on Standard and Modern, with short spinoff/parallel series involving Commander, 2HG and Legacy if it becomes really popular. For the visuals, we flash into the 'real' MTG, with planeswalker versions of MC and opponent flinging spells and creatures at each other. Lots of references to original card art, including creatures being drawn and animated in different styles depending on original artist.
Storyline: Something original. A Planeswalker learning how to do Planeswalker things from an expert Planeswalker while going through the Multiverse and getting hunted down.