Thassa's Oracle
{U}{U}
Creature — Merfolk Wizard
Oracle Text
When this creature enters, look at the top X cards of your library, where X is your devotion to blue. Put up to one of them on top of your library and the rest on the bottom of your library in a random order. If X is greater than or equal to the number of cards in your library, you win the game. (Each {U} in the mana costs of permanents you control counts toward your devotion to blue.)
Watch Out
Wins on ETB trigger resolution, not castCommon Misplay
The win condition checks devotion to blue and library size when the ETB trigger resolves, not when it enters. Opponents can respond by removing blue permanents or shuffling cards into your library. The trigger uses the stack and can be countered with Stifle effects.