Almost all of them are just, like, there
1 Nicol Bolas, Dragon-God
Youre playing Sealed and your opening hand is six lands plus the best card in the deck, a 6-mana bomb that should win the game if you can play it without being terribly behind
Then, when they enter the battlefield, either each other Creature gets -X/-X until the end of turn, and you lose X life, or you can return up to X Creature cards with a mana value of X or less from your graveyard to the battlefield, and then give them haste until the end of turn
You even get to play the card making all manner of things like Emrakul even more unfair to hideaway
Its not like they are playing Scornful Egotist (honorable mention, but not appearing on this list)