It's easy to explain, even to someone unfamiliar with the game, that a Magic deck consists of 60 cards, with a limit of no more than four copies of any particular card. It's a bit more challenging to teach them about the extra 15 cards that come along with, and yet are not part of, the deck. Harder still is the task of conveying just how important those cards are, and how vital it is to choose them carefully.
Tournament matches are typically determined by a "best two-out-of-three" set of games. For the first game, both players play with their main decks—their primary 60 cards that will be the same for the start of every match. After Game One, the players have the option to swap in any number of the 15 cards from their sideboard in an effort to make their deck better suited to winning the next game.
Technically speaking, it's legal to play with a deck of more than 60 cards, but at all times your deck must be at least 60 cards and your sideboard must be at most 15 cards. (Except in Limited. Sideboarding in Limited will be covered in a future article.)
Sideboards win tournaments. Because your sideboard cards can be more specialized—pinpoint focused for a certain task or matchup—they're often your most powerful tools. Sometimes, sideboarding can be the most important factor in determining how two decks will match up against one another. Building and using your sideboard well will be crucial to your tournament success.
Let's go over a few of the useful things your sideboard can do for you.
You sideboard with the goal of making your deck better suited for a matchup. What simpler way is there to accomplish that goal than to bring in the perfect answers for your opponent's threats?
A classic example of a sideboard card is one that destroys artifacts and/or enchantments. Except in extreme circumstances, players choose not to main deck cards like Unravel the Æther out of fear those cards will be dead—useless—against certain opponents. However, it's nice to have access to Unravel the Æther in your sideboard for when you face a deck that's particularly reliant on Thassa, God of the Sea; Jeskai Ascendancy; or any other enchantment or artifact one could possibly imagine.
Similarly, if your opponent has lots of Planeswalkers, you might want to sideboard in more answers to Planeswalkers. If your opponent is trying to win via a swarm of cheap creatures, you might want board sweepers like End Hostilities. If using a small handful of powerful creatures, then you might want spot removal like Murderous Cut.
Your sideboard lets you find the perfect tool for any job. Playing Game One ought to show you exactly what "the job" is in any particular case.
On the flip side, you can also use your sideboard to find a new threat that your opponent will struggle with. You might go about this in a number of different ways.
First, you might simply add more threats in an attempt to overload your opponent's answers. Imagine, for example, that you face a control deck that features very few creatures. During sideboarding, you get to take out some of your ineffectual creature removal and increase your concentration of threats, which ought to be tremendously helpful.
Alternatively, you might just make some minor upgrades to your existing threats. Against a deck with tons of removal, you could swap one of your two-drop creatures for Eidolon of the Great Revel and at least get 2 damage out of the inevitable exchange. If your opponent has too many blockers for your ground creatures, Mogis's Marauder might be a nice upgrade to get in some extra damage. After all, sideboarding is about perfecting your deck for the matchup, and a few minor upgrades can be a big part of that.
Most often, though, you'll sideboard with the goal of diversifying your threats. It's all about sticking in a threat that your opponent cannot effectively answer. And the more angles you can attack from, the better chance you have of doing so. When I build a green creature deck, one of my go-to sideboard cards is Nissa, Worldwaker. If my opponent is well prepared to fight my creatures (End Hostilities is a card that often gives me problems), a Planeswalker like Nissa is a great way to catch him or her unprepared.
In general, Planeswalkers and other noncreature threats tend to be good sideboard cards against slow decks.
In the old days, building your sideboard was easy; cards like the ones featured above could completely hose decks of a particular color. Today, things aren't quite this extreme, but it's still helpful to look for hate cards—single cards that are extremely effective at beating (hating out) a particular deck, color, or strategy.
A rule of thumb is that the more extreme a strategy is, the easier it will be to sideboard against. Here's a good example from the most recent Pro Tour.
Many of the cards in Lee Shi Tian's deck might look odd, and rightfully so. This is what's called a combo (combination) deck. Such decks have no interest in playing a close, fair game of Magic. Instead, they seek to set up a game state where they can do something extremely powerful—typically game-winning. You can think of it almost like they're exploiting a loophole in the game, except that it's a completely legal and valid strategy.
Lee Shi Tian's deck is built around Jeskai Ascendancy. In addition to a number of other powerful interactions, he would aim to assemble Jeskai Ascendancy, Retraction Helix, and Briber's Purse. He would cast Retraction Helix on a creature—say Rattleclaw Mystic—tap it to return Briber's Purse to his hand, cast Briber's Purse for zero mana, untap his Mystic with Jeskai Ascendancy, and repeat the process until his Rattleclaw Mystic had +1,000/+1,000 from Jeskai Ascendancy, then attack for the win.
This is an extremely powerful combo, frequently capable of winning the game on turn three or turn four. The catch (isn't there always a catch?) is that the deck tends to do poorly in sideboarded games. Even a card as simple as Erase or Unravel the Æther could destroy Jeskai Ascendancy, and the deck would cease to function properly. In this case, Erase plays the role of a hate card—a single card with a tremendous ability to change the outcome of the game all on its own.
Similarly, some players will choose to play weenie creature decks that are extremely fast and brutal. These decks tend to do quite well in Game One but, like all extreme strategies, they sometimes run into a single card—like Anger of the Gods—that can dismantle their whole strategy. Stain the Mind is a hate card against any deck that's reliant on a single card, and Tormod's Crypt is an iconic hate card against any deck trying to take advantage of the graveyard.
Any time you find yourself with extra space in your sideboard, identifying and playing with hate cards against a popular deck is a great way to improve your chances in a tournament. They give you the ability to swing a matchup in your favor at the low cost of only a sideboard slot or two.
The most interesting thing about sideboarding is that it's done in secret. Most of the time, your opponent won't even know what cards are in your sideboard, let alone which ones you'll choose to bring in for Game Two! This means that every once in a while you'll have the chance to take an opponent by surprise by employing a strategy he or she hadn't expected or prepared for.
A simple example would be a control deck with very few creatures in the main deck. If your opponent sideboards out a lot of his or her creature removal while you sideboard in a number of threatening creatures, you might be able to steal an easy win.
Similarly, take a closer look at Lee Shi Tian's Jeskai Ascendancy combo deck, shown above; he had an ingenious plan for beating people's sideboard hate cards. If people were going to bring in a lot of overly narrow cards like Erase and Stain the Mind, he would transform into a creature deck to dodge these hate cards and take advantage of his opponent's watered-down deck. He would simply catch his opponent by surprise with a giant monster—Savage Knuckleblade or Polukranos, World Eater—and steal the game.
Transform sideboards can be fun and impressive when they work out, but I recommend turning to it only as a Hail Mary, when nothing else is working. After all, sideboarding should be about perfecting your deck, not about clumsily trying to employ two conflicting strategies at the same time.
How to Build Your Sideboard
Building your sideboard is a task that's as challenging and as important as building your main deck. From my experience, though, it's typically given only a small fraction of the attention it deserves.
The Elephant Method
It can be quite difficult to hone in on the perfect 15 cards. One way to start the process is to employ the elephant method. Legendary deck builder and Pro Tour Hall of Famer Zvi Mowshowitz explains the elephant method as:
"Writing out ideal realistic lists for all matchups and then trying to make the unique cards in those lists add up to 75 cards before deciding on the specific 60 for the main deck and the specific 15 for the sideboard."
When you employ the elephant method, you're thinking of your deck as a complete 75-card unit. You consider what you'd like your deck to look like after sideboarding in each of the matchups you expect to face—you make sure you have the proper number of cards to bring in and take out in each matchup—and you construct your deck and sideboard accordingly. In short, you look at the big picture, and your sideboard is as important to the big picture as your main deck is.
One common pitfall to avoid is over-sideboarding. It's dangerous to bring in so many sideboard cards that you compromise the original game plan of your deck. In sideboarding, continue to pay close attention to your creature count, your mana curve, and the other important details of your deck's composition.
For example, if you're playing an aggro deck, you might encounter a problem if you swap out six creatures for six answer cards. You're liable to lose too much of the aggressive potential that made you choose the deck in the first place!
Similarly, if you're playing a control deck against a fast aggro deck, you might be unimpressed by a slow card-drawing spell like Jace's Ingenuity. To be sure, Jace's Ingenuity is not one of your "best cards" in the matchup, but you do need to maintain a certain density of powerful late-game cards or else you might no longer be able to win the game! Many times, I've made the mistake of sideboarding in too many cheap removal spells, only to find myself suffering from mana flood and losing the long games that my deck had been designed to win.
Practice with Sideboards
Sometimes the way two decks match up after sideboarding has virtually no resemblance to the way they match up in Game One. When this is the case, you want to know about it ahead of time instead of facing a trial by fire in the actual tournament.
Like most things in Magic, there's no secret recipe to building a perfect sideboard. The key is simply to give it the attention it deserves rather than throwing it together the morning of the tournament. Personally, in the late stages of my tournament preparation, I like to be playing virtually all of my practice games with sideboards. In preparing for a tournament, if you aren't playing any sideboarded games, or are doing so only as an afterthought, I recommend rethinking your process to give your sideboard some extra emphasis. A little bit of work on your sideboard will pay off in a big way.