This post helps cube owners and drafters decide whether to bother with a sideboard in an MTG cube by explaining what “sideboard” means in Cube (and when it actually matters), so you can run smoother drafts with fewer rules arguments.
TLDR
- In most Cube drafts, you already have a “sideboard” by default: it’s the cards you drafted but didn’t put in your 40-card deck.
- If you mostly play best-of-1, sideboarding is optional flavor. Focus on main-deckable interaction and call it a day.
- If you play best-of-3 (or you have lots of linear decks), sideboarding matters a lot more, and your cube should contain enough flexible answers to make sideboarding real.
- The only time you “need” a special sideboard setup is when you run mechanics that care about “outside the game” (Wishes, Learn/Lessons, some Companion vibes). Pick a simple house rule and move on with your life.
The hook
Sideboards are the junk drawer of Magic. That one place where you keep the cards you swear you’ll need someday, like artifact hate, graveyard hate, and that one random card you drafted because it felt powerful and then immediately realized it didn’t fit your deck at all.
So do you need a sideboard in an MTG cube? Yes and no. You probably already have one. The real question is whether your Cube night is set up in a way where sideboarding actually matters, or whether it’s just a concept you nod at politely before jamming another game.
First, what “sideboard in an MTG cube” usually means
People use “sideboard” in Cube to mean two different things:
- Draft sideboard (the default)
You draft ~45 cards, build a 40-card deck, and the leftovers become your sideboard. No extra cards required, no extra rules needed. - Constructed-style sideboard (a choice)
You want something like “15 sideboard cards” as a defined thing, either for special mechanics (Wishes, Learn/Lessons) or because your group loves the play pattern of sideboarding with intention.
Most cubes only need #1. #2 is optional seasoning, and like seasoning, it is possible to overdo it and ruin dinner.
What the actual rules say (so we’re not inventing new physics)
In Limited (Draft and Sealed), your sideboard is basically “everything you opened or drafted that you didn’t register as your deck.” You can swap cards between games as long as your deck still meets the minimum size (typically 40 cards in Draft) and you’re not doing anything that breaks the format’s construction rules.
Cube plays like Limited, even if your cards came from a lovingly curated box instead of booster packs. So the cleanest Cube answer is:
- Your sideboard is your unused drafted cards.
- You can sideboard between games.
- Your deck stays at least 40 cards.
That alone solves 90% of “sideboard in an MTG cube” debates.
When you can basically ignore sideboarding (and nobody dies)
If your Cube night looks like this:
- You play best-of-1 because time is limited,
- you rotate opponents quickly,
- you’re drafting with newer players,
- or your cube is more midrange-y “good stuff” than matchup-polarized,
…then sideboarding is not a required feature. It still exists, technically. People will still have leftover cards. But they’ll use them the way most of us use gym memberships: with good intentions and minimal follow-through.
In this kind of Cube, the better design goal is:
- Make answers main-deckable.
If interaction is playable in game one, players don’t need a sideboard to fix their entire life in game two.
When sideboarding is actually worth caring about
Sideboarding matters more when:
- You play best-of-3, especially with the same opponent.
- Your cube has fast linear decks (reanimator, storm-ish builds, hard control, hyper aggro).
- Your cube includes powerful narrow threats that demand specific answers.
- Your group likes the “draft skill” of grabbing a few bullets and knowing when to deploy them.
In higher-powered environments, sideboarding is one of the biggest skill edges. The better your decks are at doing their thing, the more valuable it becomes to have a plan for “what if my opponent’s thing beats my thing.”
Do you need dedicated “sideboard cards” in the cube list?
Here’s the practical answer: you don’t need a special sideboard pile, but you do need the cube to contain enough flexible, draftable answers that sideboarding is meaningful when you play best-of-3.
A useful rule of thumb for cube design:
- Main-deckable answers first
- Narrow hate second
- Ultra-narrow silver bullets last (or never)
Because if you fill your cube with cards that only matter in one matchup, you create packs where half the table is just hate-drafting out of spite. Which is a real strategy, but it’s also how friendships end over cardboard.
A simple framework (Good / Better / Best)
| Approach | What it means | What you gain | What you give up |
|---|---|---|---|
| Good: “Leftovers are the sideboard” | No special rules. Sideboard is unused drafted cards. | Simple, fast, beginner-proof. | “Wish” and “Lesson” cards might need a house rule. |
| Better: “Sideboard-friendly cube” | You include enough flexible answers that sideboarding matters. | Best-of-3 becomes deeper and more skillful. | You spend cube slots on interaction instead of only threats. |
| Best (for specific groups): “Supported outside-the-game mechanics” | You define how Wishes/Lessons work and maybe include a small module. | Those mechanics actually function as intended. | Extra rules, extra explaining, extra opportunities for confusion. |
The “narrow hate card” question (aka “why is this even in the cube?”)
Some sideboard-y cards are great in Cube because they’re still playable enough to draft without regret. Others are basically a sticky note that says “hope someone plays the thing this hates.”
Better sideboard cards (still reasonable picks)
These tend to be:
- cheap (so they aren’t dead when you draw them),
- broad (hit multiple archetypes),
- or have baseline utility.
Examples of broad categories (not a required checklist):
- artifact/enchantment interaction that still does something in most matchups
- graveyard interaction that isn’t completely blank if the opponent isn’t reanimating
- extra removal that’s mediocre but playable
- a second copy of an effect your deck already wants (counterspell, sweeper, threat density)
Risky sideboard cards (often rot in packs)
These tend to be:
- extremely narrow,
- expensive,
- or only good if your opponent is doing a very specific thing.
You can run these, but do it knowingly. If your cube has only one real graveyard deck, then the graveyard hate becomes a weird lottery ticket.
The real troublemakers: “outside the game” mechanics in Cube
This is where “Do you need a sideboard in an MTG cube?” turns into “Do we need a house rule, or do we ban a few cards?”
Three common offenders:
1) Wishes and “cards you own from outside the game”
In competitive settings, “outside the game” is functionally your sideboard. In casual Cube, it can mean whatever your group agrees on, which is both beautiful and horrifying.
Cube-friendly house rule:
Wishes can only get cards you drafted that are currently in your sideboard (unused drafted cards).
This keeps the mechanic meaningful without turning game two into “I brought a binder.”
2) Learn and Lessons
Learn is basically “get a Lesson from your sideboard” (or rummage if you can’t). In a normal Limited environment, Lessons live in your pool, so it’s straightforward. In Cube, it depends on how you built the list.
You’ve got options:
- Simple: Lessons must be drafted like everything else, and Learn can grab from your drafted sideboard.
- More supported: You include enough Lessons in the cube that drafting them is realistic.
- Not worth it: You don’t run Learn/Lesson cards in Cube, because you like peace.
3) Companion
Companion is its own little mini-game about deck construction and starting the game with access to a specific card. In draft-like environments, it usually behaves fine if you let players use the Companion they drafted, assuming they meet the requirement. If your group hates it, it’s also very legal to simply not include Companions in your cube. That’s the joy of Cube: you’re the boss.
A “say this out loud” script for Cube night
If you want to avoid the 12-minute pregame rules summit, steal this:
“Sideboard is just the cards you drafted but didn’t put in your deck. Between games, you can swap anything as long as your deck stays at least 40 cards. If a card says ‘outside the game,’ it can only grab from your drafted sideboard.”
Congratulations, you now run a cube like a functional adult.
What this means for a 540-card cube
A 540-card cube has a big advantage: you can afford some redundancy. That means you can include:
- enough interaction that decks can function in game one, and
- enough “toolbox” cards that sideboarding matters when you play best-of-3,
without every draft turning into “who opened the only Disenchant effect.”
In other words, 540 is large enough to support both:
- healthy main-deck answers, and
- a little sideboard spice (without the spice being the entire meal).
So… do you need a sideboard in an MTG cube?
If you’re drafting Cube, you already have one. It’s the cards you drafted and didn’t play.
What you might need is:
- a clear expectation on best-of-1 vs best-of-3, and
- a simple house rule for outside-the-game mechanics if your cube includes them.
If you do that, sideboards stop being a philosophical debate and go back to being what they were always meant to be: a place to stash answers, bluff your opponent, and pretend you definitely planned for this matchup the whole time.
FAQs
How big is a sideboard in Cube?
Usually it’s just your leftover drafted cards. If you draft 45 and build 40, you’ll have about 5 cards. Sometimes more, sometimes less.
Should Cube be best-of-1 or best-of-3?
Best-of-1 is faster and simpler. Best-of-3 rewards drafting and building a real plan, including sideboarding. Pick based on how much time you have and how sweaty your group gets.
Can I sideboard any number of cards in Cube?
In the Limited-style approach most cubes use, yes. Swap as much as you want between games, as long as your deck stays at least 40 cards.
How do Wishes work in Cube?
The cleanest house rule is “Wishes can only grab cards you drafted that are currently in your sideboard.” That keeps it fair and keeps everyone from bringing a backpack of nonsense.
Do I need to add a separate 15-card sideboard to my cube?
Not unless you’re intentionally supporting mechanics that need it. Most cubes run perfectly fine with the drafted-leftovers sideboard.