One of the hardest things about deck building is figuring out what to put into your Side Deck.
In competitive Yu-Gi-Oh, your Side Deck is a 15-card toolbox to help make your life easier over the course of a given tournament. When you're playing the best deck in the format, everybody and their mother is siding to stop it - sometimes they're even main decking cards to beat your deck. And if you're playing a rogue strategy, your Main Deck typically has some sort of anti-meta spin to it to handle the number one deckk-to-beat, while your Side Deck might have cards to make other specific matchups easier.
When you're looking at cards you might choose to side, you have to think about their over-arching purpose. Fifteen cards is not a lot. You have to choose wisely and figure out exactly what you need to optimize your matchups, and max out your chance of winning.
Take a look at just about any deck that's topped in the last six months and you'll almost always see three cards in the Side Deck. These three 'staple' side cards have proven their worth time and time again as valued members of your little toolbox. I'm sure if you look at your Side Deck, you may already be using them, and at the very least you've probably considered them before.
Harpie's Feather Duster has always been a powerhouse spell. The ability to wipe out all of your opponent's spells and traps without any cost or special restrictions is incredibly strong and can often win you the game the moment it hits the field. Ever since Harpie's Feather Duster came off the Forbidden & Limited List it's been a mainstay in the competitive scene as the best way to clear away any non-monster disruptions your opponent may have.
Dinowrestler Pankratops is another essential Side Deck card that's seen consistent play since its release. Despite its current Limited status, it still gets run because it serves as an all-purpose spot removal card, while also boasting a very solid 2600 ATK. The fact that its ability is a Quick Effect is what makes it just so darn good! Making a 2-for-1 trade with your opponent during the Battle Phase is awesome, and it gets even better if you force your opponent to use some form of protection during the Battle Phase as well.
Red Reboot another essential card and is possibly one of the most unique of the three. It's been Limited for quite some time, to the joy of control decks and the dismay of combo players. The ability to straight up stop your opponent from using any of their cards is insane. Doing it from your hand at the cost of half your Life Points? Shut up and take my LP. If it means I have the ability to combo off to the fullest that's fine, because I know my win rate is skyrocketing after Red Reboot resolves.
Depending on the format, sometimes there's a fourth member of The Essentials Club™ too, one of the strongest Continuous Trap cards ever printed: Imperial Order. It's easily considered essential in eras like 2019, when Sky Striker was running rampant as one of the best decks in the game. The strategy was so reliant on spell cards, and it made Imperial Order an absolute must to side for almost the entire yea. Nowadays it can also serve as a great 1-of counter to Dark Ruler No More for many combo decks, as a way to protect your multiple monster-based points of interaction on the field.
Imperial Order hasn't been as popular recently, but it's still popping up in Side Decks here and there as a powerful way to deal with spell-heavy decks. You should definitely still consider it when you're starting off building your side.
I can't count how many times I've lost to a floodgate. It happens. You have to accept that.
Most of the time those floodgates come in the form of Continuous Spell and Trap cards. Sometimes they're even Field Spells (I'm looking at you, Mystic Mine). Whenever I'm at my local OTS and people come to me to express their frustrations with cards like Mystic Mine or There Can Be Only One I always ask them the same thing: "What kind of backrow removal are you siding?.
You'd be surprised how many people pause at that question and realize that they might only have The Essentials, Harpie's Feather Duster and Red Reboot, as their answer.
When you think of backrow removal there are a few cards that might come to mind. Twin Twisters, Cosmic Cyclone, and Lightning Storm are the big three that see play. More often than not, you'll see a player side anywhere from three to six copies of those cards in some combination. They provide that extra bit of oomph you need to push through back-row reliant decks and play the game your way.
For many players, Lightning Storm out of the question due to its current price tag, in addition to the restrictions on it, which usually make it good only on your first turn if you're going second. Getting to play what's essentially four copies of Harpie's Feather Duster isn't always worth it if you can only play it as one of your first cards, or if you're in a losing situation.
Deciding on Twin Twisters or Cosmic Cyclone is also iffy. Can your deck afford to discard cards to activate Twin Twisters or do you need full access to all of your cards? Is the 1000 LP something you can afford to pay at the extent of banishing just one card? These are questions you have to ask yourself when you're deciding on what kinds of back-row removal you should run.
I've been messing around with different Tri-Brigade variants all format long, and I've discovered that deck can't always afford the discard for Twin Twisters. Sometimes I can't even activate Cosmic Cyclone because my opponent might have Artifact Lancea, making any of my banishing effects useless that turn. I've been running three copies of Mystical Space Typhoon instead, keeping it old-school with one of the OG removal cards.
Blowout cards don't exist in every format, but they're the types of cards that can shut down a deck entirely. Sometimes they're seen as auto-wins against certain decks, while other times they can effectively end a player's turn.
Common examples of blowout cards from formats past include Anti-Spell Fragrance against Pendulum decks; Artifact Lancea against Orcust, assuming they don't have Orcustrated Babel on the field; or Dimensional Barrier against a multitude of themes. When blowout cards have their place in a format, it's usually a good idea to try and devote some of your Side Deck space to them as they can make certain matchups infinitely easier.
As the format evolves, we sometimes see people play common blowout cards in their Main Deck. Last format, when two of the most popular decks were Dragon Link and Virtual World, Artifact Lancea was one of the best blowout cards going; many players chose to main them, even if it meant having a potentially dead card against Drytron or Zoodiac. Nowadays most players are choosing to run a set of Dark Ruler No More in their Main Deck for an advantage going second against combo decks like Dragon Link and Tri-Brigade.
Dark Ruler No More one of the best blowout cards available because of its versatility: it fits perfectly into the Main or Side Deck, because it's just so useful so consistently. Even against non-combo decks like Zoodiac Eldlich, turning off a Zoodiac Drident and a Divine Arsenal AA-ZEUS - Sky Thunder is super strong and can make everything easier for you.
Dimension Shifter a super niche blowout card because of its unique activation requirements. When you can resolve it successfully it can almost win you the game. Ogdoadic's already starting to see some popularity as a combo-heavy Chaos deck similar to what we used to see from Thunder Dragons. In discussions with many of my friends, getting to chain Dimension Shifter to Snake Rain is usually powerful enough to end the game unless they opened with their lone Called by the Grave.
Solemn Judgment been seeing play in combo sides as a blowout card too. Many combo players are choosing to side the ultimate counter trap as a way to nix blowout cards like Dark Ruler No More or Forbidden Droplet. The chance of opening with multiple copies of Dark Ruler No More are really low, so losing it to Solemn Judgment can be devastating.
The last slots in your Side Deck may just end up being generic good cards that you weren't able to fit into your Main Deck.
Just about everything right now should be running Nibiru, the Primal Being in some way. If you weren't able to fit Nibiru, the Primal Being into your main deck, it will likely end up in your side. Other situational good cards that might appear in your Side Deck can include Fantastical Dragon Phantazmay or Ice Dragon's Prison.
The standout best Side Deck card that's seeing play right now might be Alpha, the Master of Beasts. Having a 3000 ATK monster that can clear away your opponent's field and also re-summon itself? I'll happily run that. Many Dragon Link players have been opting to run three copies of Alpha, the Master of Beasts in their side because of its awesome versatility.
Monsters that summon themselves to your opponent's field are played throughout many different formats. Before it was determined that Dragon Link was the deck-to-beat in current competition, many players were running Gadarla, the Mystery Dust Kaiju as a way to deal with Barrier Statue of the Stormwinds in Tri-Brigade. Since Dragon Link's been seeing more and more popularity, Gadarla, the Mystery Dust Kaiju fallen off while players replace it with Dark Ruler No More. Sometimes your strategy might call for Kaiju monsters or even the occasional Lava Golem. Use your best judgment, but also pay attention to what's currently being played to make sure that you can still summon the monster!
The Side Deck's such an interesting part of this game. Side Deck picks say a lot about a player, and also about the metagames that they're expecting to see. Sometimes you might side too many cards for a particular matchup, while foregoing others. It's a coinflip gamble, as you'll often see nothing but the deck you're prepared for, or you'll barely see it at all and lose out because of it. Learning that perfect balance will really help you in the long run.
I've mainly been playing Lyrilusc Tri-Brigade lately, with great success at different Remote Duel tournaments, so my Side Deck's tailored around that deck. My side currently looks like this:
3 Mystical Space Typhoon
1 Harpie's Feather Duster
1 Red Reboot
1 Imperial Order
3 Solemn Judgment
3 Nibiru, the Primal Being
3 Artifact Lancea
I have a good number of cards that fit into each category: 3 essentials, 5 pieces of spell and trap removal, and the remaining cards function as both blowouts and generic good cards. There's a good balance of going-first and going-second cards, which means I can have an advantage either way. I'm currently playing three Dark Ruler No More in the Main Deck, which is why they don't appear in the side. Artifact Lancea are just obviously cards everyone should be running right now.
The theory of understanding a proper Side Deck takes a while to get used to. You won't become a master at it overnight! Use your local tournaments to test out your side in action and play in different Remote Duel servers as well! The more you widen the circle of people you're playing against, the more you'll see what cards you should and shouldn't be Side Decking!
If you ever have any questions or need help, feel free to reach out to me on Twitter or Facebook! I'm happy to help with Side Deck ideas. Until next time, good luck Duelists!