Yes, it does cost 8 mana, but in most cases, it should be a game-ending spell: exiling all creatures and letting you replay the wole board sounds super powerful
Still, it seems a bit strange to give it the number-one spot, so it's here instead
All said and done it is still a situational card and often a very poor rip off the top meaning you can't just throw this into a deck without thought and not have it cost you
Unfinity , however, was released in black border with two types of cards in the set: cards that have the acorn symbol are considered casual cards (exactly as if they were a silver-bordered card), and those that dont have the acorn symbol arent, and can be played in sanctioned/competitive formats like Commander, Pauper, Legacy and so on
Not all card art is created equal