Stroke of Genius is one of those cards players keep asking about. Here is, in plain words, what its official text says, the rulings published by Wizards of the Coast, and the combos players actually run.

Official card text

Target player draws X cards.

Complete guide

Stroke of Genius is a classic blue instant that offers unparalleled flexibility for card advantage or even a surprise win condition. Whether you are refilling your hand or forcing an opponent to draw their last remaining cards, this spell scales perfectly with the amount of mana you can generate.

Variable Card Draw

The core of Stroke of Genius is the {X} in its mana cost. When you cast this spell, you choose a value for X, and the total cost becomes that value plus two blue mana. Upon resolution, the target player must draw exactly that many cards. Because it is an instant, you can wait until the last possible moment—usually your opponent's end step—to commit your mana and maximize your draw.

Step-by-Step Resolution

First, you announce the spell and choose a value for X. Second, you choose a target player. Third, you pay the total cost. Once the spell resolves, the targeted player draws X cards one by one. If X is greater than the number of cards in that player's library, they will attempt to draw from an empty library and lose the game the next time state-based actions are checked.

Common Pitfalls

A frequent mistake is forgetting that Stroke of Genius targets a player. If your opponent has hexproof, you cannot target them to force a loss by mill. Additionally, if the target player becomes illegal before the spell resolves (for example, by gaining protection from blue), the entire spell is removed from the stack and no one draws any cards.

Strategic Timing

While it is tempting to cast this for a small amount early, it is often best saved for when you have excess mana. In the late game, it serves as a 'mana sink' that ensures you never run out of resources. In high-power formats, it is also a viable finisher in infinite mana combos to force an opponent to draw their entire deck.

Interaction examples

Fighting Through Disruption

Counterspell

You cast Stroke of Genius with X=5. Your opponent responds by casting Counterspell to stop the draw. Because Stroke of Genius is on the stack, it is a valid target for Counterspell. If Counterspell resolves, Stroke of Genius is moved to the graveyard and you draw no cards.

Delayed Gratification

Arcane Denial

If you cast Stroke of Genius and your opponent counters it with Arcane Denial, the Stroke of Genius is countered immediately. However, thanks to Arcane Denial's effect, you will still get to draw up to two cards at the beginning of the next turn's upkeep, partially compensating for your lost spell.

The Finisher

If your opponent has only 10 cards left in their library and you have 13 mana available, you can cast Stroke of Genius with X=11, targeting them. When the spell resolves, they attempt to draw 11 cards, fail to draw the 11th, and lose the game immediately.

Guide written with AI from the official text and rulings. Official English text prevails.