Your cube sideboard is every card you drafted that is not in your main deck, plus any basic lands you want. There is no 15-card limit, you do not have to swap one for one, and you may change your deck between every game of a match. Those three facts settle most arguments at a cube table, and the rest of this article covers the ones they do not.
Sideboarding is also the most under-used skill in cube. Most drafters build a deck and play it unchanged all night. The ones who win more often spent five minutes thinking about the 22 cards they did not play.
What are the actual Limited sideboard rules?
The rules are short. From the MTG Wiki’s sideboard page and the Magic Tournament Rules:
- In Limited, all unused cards in your pool are your sideboard. There is no size limit.
- You may add any number of basic lands to your deck or sideboard at any time.
- Between games of a match, you may change your deck freely, as long as it stays at 40 cards or more. You do not need to swap one card for one card. Constructed dropped its one-for-one requirement with the Magic 2014 rules update in 2013, and in Limited every unused card in your pool already counts as sideboard.
- Before game one of every match, your deck must return to the version you registered or built. In casual cube, that means the deck you built after the draft.
- Your opponent may count your sideboard at any time. You may look at your own sideboard during a game.
A 45-card pool with 23 spells in the deck leaves 22 cards in the sideboard plus the land box. That is the material you are working with.
What counts as a sideboard card in cube?
Three categories, in order of how often they matter:
1. Cards you drafted and cut. The 23rd and 24th spells, the off-color removal you took as a hate-draft, the second-color splash you abandoned. These are what you bring in.
2. Basic lands. Unlimited and free. Going from 16 lands to 17 against a slow deck, or 17 to 16 against aggro, is sideboarding. So is swapping a Plains for a Mountain to support a sideboard card.
3. Cards named by wishes and “outside the game” effects. Burning Wish, Glittering Wish, Karn, the Great Creator, and similar cards fetch from your sideboard in tournament play. In a cube, that means your unused draft picks. A Karn in a cube with a strong artifact section becomes a toolbox, and a drafter who takes Karn should keep every artifact they pass over. The MTG Wiki notes the same sideboard access applies to companions and to learn.
What does not count: cards from the rest of the cube. The box is not your sideboard. A drafter may not go to the cube after game one and pull a Pyroblast. This seems obvious and gets asked every few weeks.
When should you sideboard in cube?
Cube decks are built from 45 cards seen once, in a hurry. The build is a guess. Game one tells you whether the guess was right against this opponent, and games two and three are where you fix it. Specific triggers:
| What you saw in game one | What to change |
|---|---|
| Opponent is fast aggro | Bring in cheap blockers and lifegain; cut 5-drops; go to 16 lands |
| Opponent is slow control | Bring in cheap threats, discard, and anything with card advantage; cut situational removal |
| Opponent has three or more artifacts | Bring in the Disenchant you cut; cut the worst creature |
| Opponent’s deck is mostly one color | Bring in color hosers if the cube has them; Pyroblast, Hydroblast, and friends |
| Your deck flooded | Cut a land, add a 2-drop |
| Your deck stalled on three lands | Add a land, cut the most expensive spell |
| Opponent has a reanimation target | Bring in graveyard hate you passed over; a Scavenging Ooze is enough |
| Your 5-mana bomb never resolved | Cut it against the counterspell deck; bring in two cheaper threats |
The common thread: you are not fixing your deck, you are adjusting it to the opponent in front of you. The main deck stays the same at the start of every match.
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What house rules do cubes add?
The official rules work. Groups add rules when the official ones create awkwardness at a casual table.
Open sideboarding. Players may look at each other’s sideboards between games. It speeds up sideboarding for new players and makes the decision a conversation. Veterans dislike it because knowing the opponent’s options is information. Decide for the group.
Sideboarding time. Two minutes between games. Beyond that, players are rebuilding, not sideboarding.
No main-deck reset. Some groups let a player keep their post-sideboard configuration for game one of the next match. It saves time and lets drafters who built badly recover. It also means the deck a player drafted is not the deck they play all night. We reset; the draft should matter.
Hate-draft declaration. A player who hate-drafted a card may not play it main deck but may sideboard it in. This is a joke rule in most groups and a serious one in team draft, where it prevents a player from drafting an off-color bomb “for the team” and then splashing it. Our team format notes are in the 3v3 team draft article.
Wish restrictions. A few cubes allow wishes to fetch only from the cards the player drafted and cut, which is already the rule, and some forbid wishes from fetching cards the player hate-drafted. This is unenforceable and most groups drop it.
The duplicate voucher. If your cube runs a duplicate voucher, decide whether the second copy may live in the sideboard. Most groups say yes. The rule is described in the duplicate voucher system.
How should a drafter build with the sideboard in mind?
Three habits that turn 22 leftover cards into something useful:
Keep the pool sorted after building. Removal, creatures, lands, and “never” in four piles. When game one ends, the Disenchant is in the removal pile, not under a stack of unplayable five-drops.
Pick 24 and 25 on purpose. When choosing the last main-deck slot, ask what the deck needs against aggro and against control, and make sure the loser of that decision is at the top of the sideboard pile. The 23rd card is the one you swap most.
Late picks are sideboard picks. From pick ten onward in each pack, the choice is rarely between two playables. Take the narrow card that answers something: the Pithing Needle, the Disenchant, the Tormod’s Crypt. Over three packs that produces five or six sideboard cards that matter, and the drafter who has them wins more game threes. The general version of this pick logic is in cube draft strategy.
What about sideboarding in two-player and team formats?
In Winston, Grid, and other two-player formats, pools are 45 cards and the sideboard rules are identical. Because both players see the same small card pool, sideboarding is more predictable: you know what your opponent passed and can guess what they will bring in.
In Two-Headed Giant, the team’s unused cards are a shared sideboard, and the tournament rules allow a team to rebuild both decks from the whole pool between matches, including swapping who plays which deck. In 3v3 team draft, sideboards are individual; teammates may advise but not lend cards.
In cube sealed, the sideboard is enormous: 90 cards in the pool, 23 in the deck, 67 waiting. Sealed players should sideboard more, not less, because the odds that a better configuration exists are high.
FAQ
How big is a sideboard in cube?
Unlimited. Every drafted card not in your main deck is your sideboard, and you may add any number of basic lands.
Do you have to swap one for one when sideboarding in cube?
No. You may change any number of cards between games, as long as the deck stays at 40 or more. The deck returns to its original build at the start of each new match.
Can you take cards from the cube as a sideboard?
No. Your sideboard is only the cards you drafted. The rest of the cube is not available once the draft ends.
Do wish cards work in cube?
Yes. Burning Wish, Karn, the Great Creator, and similar effects fetch from your sideboard, which in cube is your unused draft picks. Drafters taking a wish should keep the cards they would want to find.
The twenty-two you didn’t play
The main deck is a first draft. The sideboard is the editing pass, done one opponent at a time, and most of the good players at a cube table are the ones who bother to do it. The game is the reason. The people are the point.
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