Magic, and the Fundamental Theorem of Poker

Ask experienced Spikes what the most skill-intensive card to play with or against in the history of Magic is, and you will usually get an instant that costs 3U as the answer.

Many will name Fact or Fiction.

Others will name Gifts Ungiven.

I agree with the Fact or Fiction people, but that argument is not what this article is about. This article is about applying poker theory to Magic.

Notice something about these cards? Both are extremely powerful, having long and proven histories in Standard, Modern or Extended, and even in Vintage once. Both are high impact cards and resolving one can decide the result of the game.

Both require high-stakes decisions to be made with incomplete information, and both have extremely high skill ceilings.

The results of the decision are sometimes immediately obvious – a player with a lethal spell on the stack splits a Flusterstorm against four non-counterspells, and the Fact or Fiction caster takes the 4 cards and then casts Mana Drain from their hand. Congratulations, you just got played.

But other times it does not become obvious who made the correct decisions until other decisions have been made, several turns down the track.


On the flip side, ask a less experienced player the same question, and they will usually name a Planeswalker. Planeswalkers also require high-stakes decisions to be made by both players, but because the hidden information aspect is less important to the card, the newer player can see more of the decision.

Games are won and lost on decisions to -3 or +1 Jace, Telepath Unbound, or whether to attack the Walker or the controller, but the players involved usually know if their decision was right or not quickly. This means they can identify the crucial moments of the game more accurately, and so more often associate them with the Planeswalker.


The highest skill ceilings on cards seem to come from those that require players to act on hidden information.

Compared to top players of other games, Magic players are terrible at doing this.

In Magic, hidden information is never totally hidden. It’s hinted at by decisions both players make. This should influence both how you play against acknowledged skill tester cards like Gifts, but also against cards that have nothing openly to do with hidden information.

As an experiment, play mirror match games against an opponent who plays with their hand revealed, and watch how often you win. If you normally split games with this opponent, it is reasonable to expect a 70-30 or better win record.


Poker players have a rule called “The Fundamental Theorem of Poker”.

I’ll quote it verbatim.

“Every time you play a hand differently from the way you would have played it if you could see all your opponents’ cards, they gain; and every time you play your hand the same way you would have played it if you could see all their cards, they lose. Conversely, every time opponents play their hands differently from the way they would have if they could see all your cards, you gain; and every time they play their hands the same way they would have played if they could see all your cards, you lose.”

This is every bit as true in Magic as it is in poker.



Hidden information doesn’t just matter when the Spike conventional wisdom says it does – during the resolution of spells like Gifts Ungiven.

You should treat every card you play as a skilltester card, and always look for unexpected opportunities to puzzle together clues to hidden information, and to use them.

If your Modern opponent is visibly unhappy with their 6 card hand on the draw, but then undergoes a significant release of tension upon their Scry 1, that should tell you something. Maybe it’s time to do something really unusual, like ‘Scalding Tarn, mainphase crack for Island, Thought Scour you’.

That’s not the reason Thought Scour was in your deck – you play it to fuel your own Delve spells so you can deploy a threat like Tasigur for almost nothing. But your goal should be to play as close as possible to how you would play if you could see all hidden information your opponent has, or previously had, access to. And you have strong reason to believe that your opponent’s top card completes an otherwise incomplete hand.

Just as in poker, you want to be looking for hints your opponent drops about hidden information all the time, not just during big decisions.

You will never completely achieve this goal, but you can work toward it.

  • sirgog

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