mtg arena cards for sale Planar Chaos Rare Magus of the (Foil) #104 The Gathering Mtg Arena | eBay

Play Once Upon a Time as long as you can, and cherish it before Wizards eventually realizes the card is too dang good.

Whether that's a bad thing, however, is up to the viewer

With a hefty 0/8 body, its also tough to remove, making it a great defensive piece in control and pillow fort decks

Furthermore, there are many more widely played formats (such as Tiny Leaders) I could provide a link to, but the reality is that if you include all those formats in your definition of previously banned, some person will eventually just invent a format that bans every card but basic lands, and therefore will be able to tutor all cards