Sideboarding is Magic’s darkest art, and in a format like Modern, where a single hate card can invalidate an entire strategy, knowing where to pick your battles is key to victory. Many players will take a stock list off the internet, or sleeve up a clutch of cards that they’ve identified as powerful haymakers against unsuspecting opponents, but more important than understanding what to bring in is why a card deserves its slot in your sideboard in the first place.

Modern, unlike it’s younger sibling Standard, is much more heavily biased towards proactive strategies, as the wide array of decks that can present a turn 3-4 kill and the diverse threat bases these decks operate on make it hostile to control decks. Blue-White control stands out as the only exception to the rule, and whilst heavily customisable, it’s frequent that the wrong set of answers can leave you stranded in the wrong matchup – Supreme Verdict and Path to Exile are dead against Ad Nauseum, and a set of Mana Leaks will do no good against Merfolk. Piloting any of the rest of the field then, your starting sixty is likely to be set up as the most aggressive build possible, with only enough interactive cards to push through your win condition of choice.

Once we reach for the sideboard, any card we add is thus only going to slow us down. We should consider – “What is the impact of swapping out one of my maindeck cards on executing my deck’s game plan?”. Playing an aggressive white deck, we can bring in a full four Stony Silence and Path to Exile against Affinity, however if we draw too many of these effects and too few proactive spells we will lose to an opponent assembling a mass of random 1/1s.

The critical point is to be able to draw a line, asking yourself “What will this sideboard card achieve to hamper my opponent, that has a greater impact than my worst maindeck card in the matchup?”, and also “What reactive cards do I need to be able to overcome my opponent’s hate cards?”. Playing Dredge, it’s going to be very difficult to beat a Rest in Peace if your opponent has a win condition to back it up, so you may need to reach for some Nature’s Claims or Thoughtseizes to answer it. However, each copy reduces the number of cards in your deck that power your engine (draw spells and dredgers). Too many and we won’t have enough velocity even to beat an opponent who doesn’t draw a single sideboard card.

The final point to consider is: “Can I win this matchup anyway?”. Modern is such a wide-open format, and many of the decks have strongly polarizing matchups. A Tron player may identify that they have a poor Burn matchup, and decide they need to prepare with a mix of Spellskites, Thragtusks and Chalice of the Void, but this is a heavy cost in slots. If you need upwards of four cards for a specific matchup that don’t have any value elsewhere just to give yourself even odds of winning, it may not be worth the expenditure. Remember that every Kor Firewalker you have for Burn is a slot you could have used on a Stony Silence. Modern is a wide open field with over thirty competitive decks, and lots of room still for innovation. Over fifteen rounds in a Grand Prix, you may only play against the most popular deck three or four times, and many of the less popular decks may not show up at all. In this kind of environment, the best way to angle your deck is to give yourself the best possible chance in the matchups you are competitive in, and sacrifice those you would have to contort your sideboard to beat.

Often, the best sideboard cards in the format are those that you can bring in against a variety of the field to a high impact. Discard spells out of Dredge are a perfect example – there are a number of powerful combo decks in the format (Ad Nauseum, Devoted Druid, Storm etc.) that operate too fast for Dredge to keep up, and having dedicated hate cards for each would quickly eat up our slots.  Discard spells are a great way to take a key combo piece out of an opponent’s hand to buy time, but is especially powerful as it helps to fight against opponent’s hate – having a turn 1 Thoughtseize to take someone’s Rest in Peace or Relic of Progenitus can do all the work that a Nature’s Claim can, but without taking up an additional slot in the sideboard. The same is true for countermagic – while its reign has come to an end, while Infect was running rampant one of their most powerful cards across the board was Spell Pierce; a cheap way to interact with removal spells, Night of Soul’s Betrayal, Liliana of the Veil, Anger of the Gods , Conflagrate etc, and came in against almost every matchup due to this flexibility.

So with this all in mind, you’ve sleeved up your fifteen and you’re ready for battle. Great – but how best to actually use them? Modern’s complicated, and most of its best players are those who have stuck with a single deck for a long time and understand their roles in each matchup. Even against wildcard decks you’ve never seen before, there will often be an analogy to another deck you can use to ground yourself and help you prepare – something like Allies or Slivers may be outlandish, but they operate on much the same axis as the Merfolk (creature deck aiming for a critical mass of ‘Lord’ effects). Being able to identify this will help you to react on the fly against anything from a brand new deck to a smaller innovation on an established archetype.

The best way to help you position yourself is to ask yourself “Which player is favoured at each stage of the game?”. Taking Jund Death’s Shadow for an example, much of the time they will look to play a controlling game for the first few turns, when they are setting up Delirium for Traverse the Ulvenwald, growing Tarmogoyfs and reducing their life total for Death’s Shadow. This will often follow up with an aggressive stance, trying to leverage large creatures and Temur Battle Rage to generate a quick win, as the deck has low staying power into the late game – discard spells become ineffectual when your opponent has no cards in hand, and random removal spells lose value against Primeval Titans and Elspeth, Suns Champion. Identifying that your opponent will be favoured once they have six lands in play will push you to look for earlier kills with Temur Battle Rage – in this instance, you may look to keep in all of your discard spells to clear a path for your creatures and be as aggressive as possible in trading resources, but shave on removal spells. Up against an Elves deck, if you are able to execute a disruptive game plan and remove their key threats with discard and Terminates, you will overpower them as the game goes on and your Death’s Shadows and Tarmogoyfs outgrows your opponent’s threats.

Sideboarding is much more art than science, and much of your role, your slots and your chance in a matchup can only be learnt through trial and error. Where are you getting your edges, and which matchups are you struggling to understand? Let me know in the comments below!