Now that you’re familiar with different deck archetypes, it’s time to round out your education with a closer look at side decks. If you want your deck to work, it needs to be more than a random pile of cards you like. The same goes for a side deck. Before you can choose cards for a side deck, you need to analyze your metagame and learn what functions your side deck serves. There are several basic strategies that lead to effective side deck builds, and each type of side deck effects game play differently. Once you understand the differences between them, it will be easier to build a beneficial side deck.

There are four basic categories of side decks, though you should always expect to see rogue strategies alongside the standard ones. Most side decks, however, employ an Expansion, Tech, Conversion, or Balanced strategy. These aren’t official terms, but they’ll do for the purposes of this article. You may know the various strategies by different names in different areas, but you’ll always recognize them by their functions. We’ll examine each category to see how it’s constructed, what functions it serves, and which ones go best with which archetypes.

Let’s begin with Expansion. As the name implies, Expansion-based side decks expand upon the main theme of the deck . . . nothing too earthshaking there. A duelist would put cards in an Expansion side deck that he or she would like to have the option of using but wouldn’t want to include in the main deck. There are plenty of reasons to use this type of side deck, from experimenting with a new deck that still needs fine-tuning to testing unfamiliar cards that might improve a deck. It’s also not surprising to see a duelist use this type of side deck if he or she knows the local metagame and wants to plan for it. For instance, you might main deck two copies of Don Zaloog in a Control deck and side deck a third to be used as needed. It’s a good way to subtly adapt your deck between duels. This type of side deck is a good choice for most decks and can really help a duelist develop a thorough understanding of an archetype.

Now let’s look at Tech. You may have heard that term used to describe when a duelist is planning to side in cards that are great against specific decks. So, a Tech-oriented side deck consists of cards that are targeted to hurt individual decks—generally those that are popular in that duelist’s metagame. Often, the cards that do this best aren’t key to a deck. Side decking them means they won’t take up wasted space in the main deck, but they will be available when needed. A duelist might not main deck Necrovalley if he or she isn’t playing a Gravekeeper deck, but that duelist could have three in the side deck for play against a Chaos deck. Tech side decks work for just about any kind of deck, especially if that deck relies on a very specific strategy that can be disrupted or has a weakness against a popular deck in the same metagame.

You’ll find that many side decks are actually a mix between Expansion and Tech. This provides a bit more flexibility in a varied metagame. If a duelist commonly faces a range of deck types rather than one dominant archetype, then a mixed side deck is an efficient way to get the most potential out of a deck.

As the name suggests, Conversion side decks contain a set of cards that go into the deck as a group to completely change the focus of the deck. A duelist usually thinks carefully when he or she side decks, choosing which cards would make the main deck more competitive in the current matchup. A Conversion side deck, however, typically eliminates that selection process by using all fifteen cards to change the main deck from one type to another. A Beatdown deck might change into a Burner deck, or a Control deck might shift to a Gravekeeper deck. You need to be a skilled duelist to make this type of side deck (or main deck, for that matter) work, but it can be devastatingly effective when handled properly. Any opponents that face this kind strategy usually have no idea what hit them.

Converting a non-Gravekeeper deck to a Gravekeeper deck seems to be the most popular Conversion side deck strategy now, especially since the three Necrovalleys in that side deck are useful by themselves against Chaos decks. Switching a Lockdown engine into another kind of deck can also be very successful, since three Gravity Binds and two spell-negating traps take up only one third of the side deck. That leaves ten more spaces for the appropriate monsters and some other spells or traps. Bear in mind that the loss of spell and trap removal in the Advanced format makes Gravekeeper and Lockdown even more appealing, since field control becomes harder to break through. Obviously, Conversion side decks are specifically meant for decks that can handle the change. Exodia to Chaos, for example, probably won’t work, but Beatdown to Burn, Control to Gravekeeper, or Water Tribal Beatdown to

A Legendary Lockdown all work well.

Now let’s look at Balanced. This one is a bit like Expanded and a bit like Conversion. The Balanced side deck is used primarily by hybrid players and allows the duelist to tilt his or her deck from one strategy to another. Currently, the most likely examples would be Chaos Control/ Chaos Beatdown and Control/Beatdown. The similarities to both Expansion and Conversion are easy to spot—the side deck both expands the scope of the deck and converts it from one strategy to another. Skilful card choices in both main and side decks will give the duelist a great deal of flexibility, allowing him or her to shift between strategies. A hybrid that was previously a 50/50 split can be changed to a 60/40, 70/30, 80/20, 90/10, or 100/0 split—whatever the situation requires. Hybrid players love these side decks, since they make an already frustrating deck type even more annoying to play against. The opponent has to second-guess what he or she will face in each duel. It takes a good bit of skill and practice to really pull this strategy off, but it’s incredibly worthwhile. Masatoshi Togawa used this technique to win the 2004 World Championships.

Remember that a side deck must always be exactly fifteen cards. You can’t add cards into your side deck if it will give you more than three copies of any unrestricted card, two copies of a restricted card, or one copy of a limited card total between your main and side deck. Cards forbidden in your deck are also, of course, forbidden in your side deck.

I hope you’ve enjoyed this overview of the different types of side decks. What will work best for you? Expansion type side decks are the easiest to play and work with almost every type of deck. If your metagame is dominated by a particular kind of deck, then Tech might level the field for you. A mix of both will give you more, but shallower, options for altering your deck. If you’ve got a fair grasp on different deck types, Conversion will keep the game interesting for you and confusing for your opponent, and Balanced will really bring out the utility of a hybrid deck. Pick what you think will work best with your deck and your metagame, and then experiment to see what helps your deck the most.