Mystical Tutor | What is a Sideboard in Magic: The Gathering?

Greg Montique
Jun 2
3 min read

If you’re just getting into Magic: The Gathering, you’ve probably heard the term “sideboard” used pretty frequently, especially when talking about formats like Modern, Pioneer, or Standard. So what is a sideboard in Magic? Simply put, a sideboard is a small set of extra cards (usually 15) that you keep outside your main deck. You use them in between games in a match (generally best of 3) to help you fit your deck to better handle what your opponent is doing.

Let’s break it down and talk about how a sideboard works, what kinds of cards you should include, and how to use it effectively.

So What is a Sideboard in Magic?

In most competitive formats, you play best-of-three matches. That means your first game is played with your original deck, but after that, you get a chance to swap cards in and out between your main deck and your sideboard. This lets you adjust your game plan based on what you’ve seen from your opponent.

Digital card game interface displaying a selection of Magic: The Gathering cards. Cards exhibit fantasy artwork and text; a sideboard on the right. — Note the sideboard on the right

The idea is to cover your weaknesses or improve your odds against specific strategies. For example, if your deck struggles against graveyard-heavy decks, you can slide in cards that exile the graveyard. If you’re up against control, you might bring in cards that are harder to counter or provide extra pressure.

What Can You Put in a Sideboard?

A sideboard can hold up to 15 cards, and these can be any legal cards in the format you’re playing—just like your main deck. The only big rule in formats like Modern or Legacy is that your sideboard and main deck combined must still follow deck-building rules, like the four-of rule (no more than four copies of a non-basic card).

Here are some common types of sideboard cards:

Magic card "Rest in Peace": A serene scene with a woman under pillars, light pouring down. Descriptive text and game details are included.

1. Hate Cards

These are cards that target specific decks or strategies.

Example: Rest in Peace (shuts down graveyards)
Example: Shatterstorm (destroys all artifacts)

Magic: The Gathering card "Negate" shows a figure in a cloak casting a blue and white energy spell. Text describes countering a noncreature spell.

2. Answers

Sometimes your deck doesn’t run certain types of removal in the main deck. Your sideboard can help fix that.

Example: Disenchant (to deal with artifacts and enchantments)
Example: Negate (to counter noncreature spells)

A fantasy card titled "Biovisionary" features a human wizard in a glowing lab with green and blue hues, crafting life forms in capsules.

3. Alternate Win Conditions

In some matchups, your main strategy might not be good enough, so you swap in another way to win.

Example: A control deck might add a powerful creature or planeswalker post-board.

Mystical figure in white robe with glowing eyes raises hands amid swirling shadows. Text reads: "Thoughtseize, Sorcery." Eerie atmosphere.

4. Flex Cards

These are cards that don’t necessarily counter one specific strategy but give you more play in certain matchups.

Example: Duress or Thoughtseize against combo or control decks

How Do You Use a Sideboard?

After Game 1 in a match, both players are allowed a few minutes to “sideboard.” You can swap in any number of sideboard cards, but your main deck must still contain the minimum number of cards (usually 60 for most formats, 100 for Commander if you’re using a wishboard).

This is when you think, “Okay, my opponent is playing a fast aggro deck. I need to slow things down.” You might take out some slower cards and bring in life-gain spells or more early-game blockers.

A Quick Example

Let’s say you’re playing a blue-white control deck and you run into a red aggro deck. After Game 1, you might:

Take out: Some counterspells and card draw that are too slow
Bring in: Timely Reinforcements, Celestial Purge, and Aether Gust

You just gave yourself a better chance to survive the early turns and get to your win condition.

Tips for Building a Sideboard

Know the meta: Build your sideboard with common matchups in mind.
Don’t overdo it: Don’t try to cover everything—focus on your worst matchups.
Practice sideboarding: Actually test your deck with and without sideboard cards. Knowing what to take out is just as important as knowing what to put in.
Stay flexible: Some cards will do double duty across matchups. Those are golden.

Sideboarding in Different Formats

Most constructed formats like Standard, Pioneer, Modern, and Legacy use 15-card sideboards. Commander (EDH) doesn’t usually use a sideboard, though some players build one for casual use or house rules. In Limited formats like Draft or Sealed, every card you don’t put in your main deck effectively becomes your sideboard.

Final Thoughts

So what is a sideboard in Magic? It’s your secret weapon. It’s not just a pile of extra cards—it’s a vital part of your strategy that lets you adapt to win. As you play more and get a feel for what your deck struggles with, your sideboard becomes a powerful tool to close the gap and surprise your opponents.

Sideboarding well is one of those skills that separates casual players from competitive ones. Start practicing it early, and you’ll see your game improve in a big way.