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Thassa's Oracle
Creature — Merfolk Wizard
rare
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 in the mana costs of permanents you control counts toward your devotion to blue.)
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Semantic Tags
Devotion-based strategies — caring about colored mana symbols in mana costs.
Triggers when a creature or permanent enters the battlefield. Prime blink targets.
Cards that directly win the game or threaten to end it quickly. Includes 'you win the game' effects and massive threats.
A card or token on the battlefield. See rule 110, “Permanents.”
Cares about or manipulates the top card(s) of your library. Includes scry, surveil, and top-deck payoffs.
Cares about or manipulates the top of library — Sensei's Top, miracles, Future Sight.
Format Legality
Price history
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Printings (7)
| Set | Rarity | TCGplayer | Card Kingdom | Cardmarket |
|---|---|---|---|---|
| Mystery Booster 2#175 | rare | · | · | · |
| Secret Lair Drop#1280 | rare | · | · | · |
| Magic Online Promos#79909 | rare | · | · | · |
| Theros Beyond Death Promos#73s | rare | · | · | · |
| Theros Beyond Death#73 | rare | · | · | · |
| Theros Beyond Death Promos#73p | rare | · | · | · |
| Theros Beyond Death#308 | rare | · | · | · |
Related Rules
If an ability would produce one or more mana of an undefined type, it produces no mana instead.
Some abilities produce mana based on the type of mana another permanent or permanents “could produce.” The type of mana a permanent could produce at any time includes any type of mana that an ability of that permanent would produce if the ability were to resolve at that time, taking into account any applicable replacement effects in any possible order. Ignore whether any costs of the ability could or could not be paid. If that permanent wouldn’t produce any mana under these conditions, or no type of mana can be defined this way, there’s no type of mana it could produce.
To “tap [a permanent] for mana” is to activate a mana ability of that permanent that includes the {T} symbol in its activation cost. See rule 605, “Mana Abilities.”
An ability that triggers whenever a permanent “is tapped for mana” or is tapped for mana of a specified type triggers whenever such a mana ability resolves and produces mana or the specified type of mana.
A replacement effect that applies if a permanent “is tapped for mana” or tapped for mana of a specific type and/or amount modifies the mana production event while such an ability is resolving and producing mana or the specified type and/or amount of mana.
If an object’s enters-the-battlefield triggered ability or replacement effect refers to X, and the spell that became that object as it resolved had a value of X chosen for any of its costs, the value of X for that ability is the same as the value of X for that spell, although the value of X for that permanent is 0. This is an exception to rule 107.3i.
The tap symbol is {T}. The tap symbol in an activation cost means “Tap this permanent.” A permanent that’s already tapped can’t be tapped again to pay the cost. A creature’s activated ability with the tap symbol in its activation cost can’t be activated unless the creature has been under its controller’s control continuously since their most recent turn began. See rule 302.6.
The untap symbol is {Q}. The untap symbol in an activation cost means “Untap this permanent.” A permanent that’s already untapped can’t be untapped again to pay the cost. A creature’s activated ability with the untap symbol in its activation cost can’t be activated unless the creature has been under its controller’s control continuously since their most recent turn began. See rule 302.6.
Rulings
Colorless and generic mana symbols ({C}, {0}, {1}, {2}, {X}, and so on) in mana costs of permanents you control don't count toward your devotion to any color.
If you put an Aura on an opponent's permanent, you still control the Aura, and mana symbols in its mana cost count towards your devotion.
If an activated ability or triggered ability has an effect that depends on your devotion to a color, you count the number of mana symbols of that color among the mana costs of permanents you control as the ability resolves. The permanent with that ability will be counted if it's still on the battlefield at that time.
If your devotion to blue is zero at the time the triggered ability of Thassa's Oracle resolves, you don't look at or move any cards in your library. If you have no cards in your library, you win the game.
Hybrid mana symbols, monocolored hybrid mana symbols, and Phyrexian mana symbols do count toward your devotion to their color(s).
Mana symbols in the text boxes of permanents you control don't count toward your devotion to any color.