Kicking off the celebrations of Magic the Gathering's 30th anniversary is Dominiaria United
and a Vaporeon 2007 Holo card, worth over $60,000
I see this being pretty damn playable, especially in versions of those decks that make treasures, can ramp with green, or can do big mana stuff with devotion and cards like Cabal Coffers
It will not solely be about Old School it should be more general, and I will use examples from other formats (even though, surprisingly, most of the examples can actually also be found in Old School it continues to amaze me how complex the game is even when you just play the first couple of card sets)
Can the archetypes that lost key cards stay afloat
For just two mana, you can morph Shapeshifter to copy any creature on the battlefield, and you can reset it on every upkeep