MTG Sideboard Guide — How to Build One

I used to build sideboards the night before a tournament by grabbing fifteen random "good cards" that did not make the main deck. My results reflected that approach: I won game ones and lost matches. It took a frustrating 2–5 finish at a Pioneer RCQ to finally sit down and build a real sideboard plan. The difference was immediate. My next event, same deck, same meta—I went 5–1, and the only thing that changed was having a written plan for what came in and out for every matchup.

This guide covers everything I have learned about sideboarding: the theory, the strategies, the common cards, and the step-by-step process I use before every competitive event.

What Is a Sideboard?

A sideboard is a set of exactly 15 cards that exists alongside your main deck. In best-of-three (BO3) matches, after game one, both players can swap any number of cards between their main deck and sideboard. The only rules: your main deck must stay at its starting count (usually 60), and your sideboard must stay at 15. You can bring in zero cards or fifteen—it is entirely up to you.

Sideboards exist because no main deck can be good against everything. A deck built to beat aggro will struggle against control, and vice versa. The sideboard lets you adjust your strategy between games to shore up weak matchups without weakening your overall game-one plan.

In best-of-one (BO1) formats like Arena ladder, there is no sideboarding. This is why BO3 is considered the more skill-intensive and competitive format—sideboard construction and sideboarding decisions add an entire dimension of gameplay.

Sideboard Strategies

Hate Cards

Hate cards are cards designed to shut down specific strategies entirely. They are the highest-impact sideboard cards because they can single-handedly win matchups that would otherwise be unfavorable. The key examples:

Silver Bullets

Silver bullets are narrow cards that answer specific problems. Unlike hate cards that shut down entire strategies, silver bullets answer individual threats or situations:

Run silver bullets as 1–2 copies for matchups you expect to face occasionally. They are not worth a full playset because you only bring them in for specific opponents.

Flexible Answers

Some sideboard cards are good against multiple matchups. These are the most valuable sideboard slots because they earn their space more often:

Transformational Sideboarding

This is the advanced strategy: your deck completely changes its game plan after sideboarding. A combo deck that boards into a control plan with counterspells and removal. An aggro deck that boards in planeswalkers to go over the top. The goal is to make your opponent's sideboard cards irrelevant.

Example: I played a Modern Creativity combo deck that sideboarded into a fair Izzet control plan against opponents who brought in artifact hate and combo disruption. They kept hands with Pithing Needles and Surgical Extractions, and I just countered their spells and beat them with Ragavan and Ledger Shredder. Their sideboard cards were dead, and mine were live.

Transformational sideboarding requires practice and dedicated sideboard slots, but it is the most rewarding sideboard strategy when executed correctly.

Building Your Sideboard: Step by Step

Here is the process I follow before every competitive event:

  1. Check the metagame. Look at recent tournament results for your format. What are the top 8–10 decks? What percentage of the field do they represent? Focus your sideboard on the top 5–6 archetypes.
  2. Identify your worst matchups. Play or mentally walk through each matchup. Which ones do you lose game one more than 50% of the time? These are where your sideboard slots should go first.
  3. Find targeted answers. For each bad matchup, identify 2–4 cards that meaningfully improve it. Prioritize cards that are good against multiple matchups.
  4. Write a sideboard guide. For every matchup you expect, write down what comes IN and what goes OUT. This is the step most players skip, and it is the most important one. Do not figure this out at the table under time pressure.
  5. Count your cuts. If you are bringing in 5 cards against Burn, you need to identify 5 cards in your main deck that are worse in that matchup. If you cannot find 5 cards to cut, you are over-sideboarding.
  6. Do not over-sideboard. Bringing in 8+ cards dilutes your deck's core strategy. Your main deck was built to do something well—do not undo that. I try to keep swaps to 3–6 cards per matchup.
  7. Test and iterate. Your first sideboard plan will have mistakes. Play games, notice what cards are dead in your hand, and adjust. The best sideboard plans are refined over 20+ matches, not created in one sitting.

Format-Specific Sideboard Guide

Standard

Standard sideboards tend to be broader because the metagame shifts frequently with new set releases and bans. Focus on flexible answers rather than narrow hate. Key considerations:

Pioneer

Pioneer has a more stable metagame than Standard, so your sideboard can be more targeted. Almost every Pioneer sideboard needs:

Modern

Modern is the most diverse format, so your sideboard needs to cover a wide range of strategies. My approach: dedicate 2–3 slots to each of the top 4–5 matchups, plus 2–3 flexible slots.

What to Cut When Sideboarding

Knowing what to bring IN is only half the equation. The other half—what to take OUT—is where most players struggle. Here are the principles I follow:

Common Sideboard Mistakes

Further Reading

Related Guides & Tools

Use our Hypergeometric Calculator to compute the odds of drawing your sideboard cards. Read the Manabase Guide to make sure your post-board mana still works. Check the Banned & Restricted List for format-specific legality, learn what each format demands in our Formats Explained guide, and browse the community deck gallery for proven sideboard plans.

Frequently Asked Questions

How many cards should I sideboard in per matchup?

Aim for 3–6 cards per matchup. Bringing in more than 6 risks diluting your deck's core strategy. Some matchups only need 2–3 targeted swaps to flip from unfavorable to favorable. Write out your sideboard plan beforehand so you know exactly what comes in and what goes out.

What are the best sideboard cards in Modern?

Top Modern sideboard staples include Leyline of the Void and Rest in Peace (graveyard hate), Engineered Explosives and Brotherhood's End (sweepers), Blood Moon and Magus of the Moon (land disruption), Flusterstorm and Mystical Dispute (counter magic), and Surgical Extraction (combo disruption). The best choices depend on your deck and the current metagame.

How do I decide what to sideboard in and out?

Write a sideboard guide for each common matchup: identify which of your main deck cards are weakest in the matchup and which sideboard cards address the opponent's strategy. Generally, cut situational cards that don't impact the matchup and bring in targeted answers. Avoid over-sideboarding—swapping too many cards can dilute your deck's core gameplan.

Should I sideboard differently on the play vs. the draw?

Yes. On the play, you want proactive cards and threats because you have tempo advantage. On the draw, reactive cards like removal and counterspells are better because you see one extra card and need to answer your opponent's faster development. Some players keep two columns in their sideboard guide: one for play, one for draw.