I had not heard that phrase, but I imagine it refers to the recently printed Oko, Thief of Crowns. A card that dominated every format until it was banned in all but Legacy, Vintage, and EDH. It is (almost) universally agreed to be the most busted Plainswalker in Magic. And it is unique in that when you first read the card you think ‘meh, no big deal’... then you play against it and lose every time.
