You dont need a big reason, just a real one: Snapcaster Mage alongside removal, countermagic, and so on
Best of the Best I always like to call out the best possible card to open in each set so that when you watch the Pro Tour broadcast you'll know what the featured player is really, really hoping to open
When you play a best-of-three match, you have the opportunity to switch cards between your maindeck and sideboard to improve your chances in the next games
Ideally, WotC would like to not be shake up formats with bans and unbans, but across formats ranging from Alchemy to Vintage, there has often been a couple a year for a while
Its too good
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