What blocks a card, and what is only a note
More to explore · beginner
When the deck builder checks a card, every finding is one of two kinds. Only the first kind can stop you adding a card or finishing a deck, and even then you always get choices.
Structural problems (these can block)
A structural problem is true of all 100 cards at once, whatever you draw. The list is short and closed:
| Problem | Example |
|---|---|
| Color identity | A card has a color your commander does not have. |
| Format legality | The card is banned in Commander, the deck has two copies of a non-basic card, or it is not 100 cards. |
| Bracket | The card is a Game Changer in a Bracket 2 deck, or it completes a combo your bracket does not allow, or it adds mass land denial or a chain of extra turns. See Commander Brackets. |
| Game plan | The deck has no way to win at all, or nothing in it that makes one of your commander's colors of mana. |
| Your declared budget | You set a budget and this card takes the deck over it. There is no budget unless you set one. |
When one of these fires, the builder offers choices: keep the card in the Pile, change the target (a higher bracket, a bigger budget), or cancel. Moving a card to the Pile is never blocked, so nothing is lost.
Play notes (these never block)
Everything else is a play note. A play note depends on a particular card being drawn, cast and still on the table at the right moment. One such card in a 99-card library is not a reason to change the other 99.
A good play note names what can happen, says how often, and says how to play around it. It keeps your plan.
Why: how often you actually see a card
A Commander library has 99 cards. By turn N on the play you have seen 7 + (N - 1) of them.
| Cards seen | One copy | One copy plus four cards that can find it |
|---|---|---|
| 7 (opening hand) | 7.1% | 31.2% |
| 11 (turn 5) | 11.1% | 45.2% |
| 16 (turn 10) | 16.2% | 59.4% |
Count tutors as copies. A card that can search for another card makes that card much more likely to show up. The builder counts them when it shows you odds.
Seeing a card is the loosest bar. It still has to be cast, resolve and survive to matter.
You decide how to play
Even when both cards show up together, you choose what to cast and when. Three other players are changing the board every turn. The builder reports the note and the numbers; the decision is yours.
Where this comes from
This is the site's deck-evaluation doctrine, the same text the Ask AI assistant reads before it suggests cutting a card.