This is all from personal perspective, so Ill undoubtably either miss one of your favorites or leave it off intentionally
Interaction You cant play cEDH without it, and you also cant really do a commander-centered combo deck without it, especially so
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Aside from categories like instant, creature, and planeswalker, cards in Magic: The Gathering can fulfill specific roles like spot removal, utility lands, and certainly board wipes
This is certainly less powerful than Second Sunrise, a card that singlehandedly fueled a degenerate combo deck (and that has a similar effect to a six-mana card), but that doesnt mean it isnt also broken
Naturally, Emrakul leaves destruction in its wake, so who knows if anyone will remain after it passes through the new world