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, and so on) in mana costs of permanents you control don't count toward your devotion to any color.Thassa’s Oracle offers a compact finish for blue decks that can reduce their library to a sufficiently small size. Its entry ability looks at cards based on your devotion to blue and can win the game if that devotion is at least the number of cards left in your library. Without that setup, it provides limited top-deck selection on a small creature.
Demonic Consultation is a common partner. With Oracle’s trigger on the stack, naming a card absent from your library can let Consultation exile the library before the trigger resolves. Tainted Pact can serve a related role, but its sequence stops on a repeated card name, making a library with distinct names important. That consideration includes the names of basic lands.
The win check happens as Oracle’s ability resolves. Removing Oracle does not automatically stop an empty-library win, because zero devotion is still at least zero cards remaining. Opponents instead need interaction that changes the relevant outcome, such as stopping the trigger or disrupting the library-emptying spell before the win condition is satisfied.
Outside a dedicated combo, Oracle can be useful after a deck has drawn or milled most of its cards, but ordinary entry does not draw a card into your hand. Committing to an empty library also leaves little room for a failed attempt followed by a forced draw. Build the protection and timing plan around the entire sequence, ensuring the deck can resolve the entry trigger under the conditions that actually produce a win.
