My understanding is, your commander deck is 100 cards. And you take commander/companions etc. out of your deck before you start and put them in the command zone.

The smallest library I can come up with, is 97 cards. Where you start with a pair of commander partners, and a companion.

Is there a way to make your library even smaller?

Addendum: I asked the question thinking of the "size of initial library" version of the question. i.e. identifying if there are any rules loop holes for deck construction that could reduce the deck size. That said, Allure's answer is awesome, and makes it clear that there are ways "in game" to get to a smaller library that could be important for some decks, I hadn't thought of that avenue, and find that to be a fine answer as well. Even if that wasn't my initial question.

  • 5
    The companion isn't in your deck, it's in your sideboard. That example starts with 98 cards.
    – murgatroid99
    Feb 16 at 3:28
  • A companion is card number 101, it does not count towards the 100 cards in a commander deck and thus won't reduce the cards in the library.
    – Andrew
    Feb 17 at 0:43
  • Re "there are ways "in game" to get to a smaller library that could be important for some decks", it's actually common for Vintage Dredge decks (which are entirely reliant on finding Bazaar of Baghdad in their starting hand) to run 4x Serum Powder. See example list mtgtop8.com/event?e=52325&d=588461&f=VI. These decks are happy to mulligan all the way down to 1 card, to find Bazaar.
    – Allure
    Feb 19 at 0:03

2 Answers 2


As far as I'm aware, the answer is 98:

  • A companion does not count as part of the 100 cards; refer to comprehensive rule 702.139a: "Before the game begins, you may reveal one card you own from outside the game with a companion ability whose condition is fulfilled by your starting deck" (my emphasis).
  • You can never have more than two Commanders; refer to comprehensive rule 702.124g: "no partner ability or combination of partner abilities can ever let a player have more than two commanders." "Partner abilities" here is defined by 702.124a and includes all of the "base" partner, partner with [name], friends forever, backgrounds and Doctor's companion.
  • While it's difficult to prove a negative, I'm going to assert there's nothing else which can allow you to reduce the size of your starting library.

(Rules references from the 2024-02-06 Comprehensive Rules)

  • Technically speaking, there is another mechanic that allows you to reduce the size of your starting library: If you for some reason do allow ante cards in your group (which would be a deviation from the rules, since they are normally banned for Commander and all other formats), but don't play for ante, you get to remove those cards from the deck before playing. There are nine such cards, which means that the actual smallest starting deck size would be 89 under these very specific and constructed conditions. Feb 16 at 13:10
  • 3
    @TheThirdMan If you're looking at cards which aren't legal in Commander, also Advantageous Proclamation, and probably some un-set cards as well. But at some point you have to start restricting things to things legal in the format as defined by the rules. Feb 16 at 14:34

You can play Serum Powder and exile 7 cards if you draw it in your opening hand, therefore "starting" with 91 cards.

You can play Shahrazad with 0 cards left in your library, to start with 0 cards. (But this card is banned in Commander ...)

Karn Liberated can also restart a game with a smaller library. It's easy to imagine a situation where Karn exiles everything and you start with 0 cards.

  • 4
    The Serum Powder example doesn't make sense to me. You only use Serum Powder like that after you have drawn an opening hand, and if you're counting from that point, the starting library size is always 7 fewer cards, because your opening hand isn't in your library at that point.
    – murgatroid99
    Feb 16 at 3:32
  • 3
    I know what Serum Powder does. I guess my point is more that if you say that Serum Powder is reducing your starting library size, then that means that you are counting the starting library size after drawing your opening hand. That means that the default commander starting library size is 92 (-1 for commander, -7 for opening hand), and the size with Serum Powder is 85 (-7 for exiled hand). But that's clearly not how the question defined it because it (incorrectly) states that the minimum they could come up with was 97.
    – murgatroid99
    Feb 16 at 4:02
  • 5
    If you look through the "starting the game" procedure in rules section 103, you start with a deck, and then in rule 103.3 you shuffle that deck and it becomes your library. I don't see any reasonable way to define "starting library" other than "your library, at the very start of its lifetime as your library".
    – murgatroid99
    Feb 16 at 4:21
  • 2
    In an effort to describe why it would be relevant: There are two reasons I can think of why a player was to reduce their deck size: To increase the chance of drawing a certain card, and to reduce the library to zero cards as easily as possible. Serum Powder appears to be helpful with both, and while I completely agree with @murgatroid99 here, I still consider this a helpful answer for the stated reason - although I will say I would prefer a rephrasing to that end as well. Feb 16 at 13:16
  • 1
    Is the 90 cards value correct, since apparently companions aren't part of the 100?
    – JonTheMon
    Feb 16 at 17:51

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