“Recursion” is a TCG term that generally refers to retrieving cards from a discard pile. In this case, it means taking cards back from the graveyard. In a general sense, it can mean any kind of card retrieval—but if you want to go with the strictest interpretation, recursion means a card that goes from the graveyard to the hand. How convenient, then, that this is the context in which we’ll explore recursive mechanics today.

The first important thing to understand about hand recursion is this—any card “recurred” to your hand gives you a piece of card advantage. Recursion has the same mathematical effect on your card count as drawing a card does. What do we like to have in our hand? More cards, of course. Generally speaking, you can only draw a card once per turn, but recursion can open up lots of possibilities. Think about that for a second and let the ramifications sink in.

For example, Pot of Greed gives you a single piece of card advantage. You activate it (decreasing your card count by one) and draw two cards. You lose one card and then go up two cards, but your net profit is a single card. If a recursive effect is generated by a card that stays on the field, you’ve essentially accomplished the same thing. Yes, you’re gaining a single card instead of the two that Pot of Greed offers, but you’re not losing a card in the process. That means the net profit from Pot of Greed is, in a strict mathematical sense, the same as the net profit from a card like Magician of Faith.

However, hand advantage and card advantage are two separate things. Your “card presence” counts the number of cards you control on the field and the number of cards in your hand, while your “hand presence” means only the cards you hold in your hand. When I say “Magician of Faith provides the same mathematical advantage that Pot of Greed offers,” I’m speaking from the viewpoint of card advantage. From this view, Magician of Faith isn’t lost. It moves from the hand to the field, so under the logic of that system, it never becomes a -1 in card advantage. But if we evaluate the same play from the perspective of hand advantage, Magician of Faithwould be considered a -1 in hand advantage, and its recursive effect would only balance out its own use and loss from the hand.

Are you still with me? The last few paragraphs were kind of complicated, but now you know the basic mathematical theory behind the overall concept of card advantage. Let’s move on and look at some finer points to investigate the advantage that recursion can have over raw drawing power.

I’d say the most obvious benefit to recursive effects is the choice they offer. Drawing from the deck is a random prospect—will you topdeck exactly what you need, or will you pull a totally dead card? Recursive effects are never completely random, as they ask the controller of the effect to designate a target. This means that in effect, you’re turning your graveyard into a searchable index of cards you can use later on in the duel. Choice increases options, and options win games by keeping you unpredictable and ready with the appropriate response to your opponent’s moves.

There are plenty of ways to exercise that power of choice. Recursion can allow you to reuse Limited cards that you wouldn’t otherwise be able to activate or summon more than once per game. The Serial Spell Abuse deck wins games by reusing Pot of Greed or Delinquent Duo over the course of a duel in order to generate enough advantage to completely overwhelm an opponent. There are even better options, though—remember our previous discussion on Pot of Greed? You’ll lose Serial Spell, and perhaps some other cards with it, but other recursive cards can stay on the field after giving you back the powerful card of your choice. I think we’ve all faced Magician of Faith (and its little friend, Tsukuyomi, who just won’t get off the field) with devastating results.

Recursive effects are also handy for their ability to get a second use out of a card that isn’t Limited. If you can rely on recursion to reuse a card that you don’t necessarily want to run multiple copies of in your deck, you’ve freed up space for other cards. If you want to keep your card count as close as possible to 40 cards, this can mean that you’ll be making some tough choices. If you can recycle single copies of certain cards, then go for it. All you’re doing is keeping more options available. This works on two fronts: you can afford to keep your decklist varied, and you’ve kept the option of getting multiple activations or summons from a single copy of a card.

Anyway, let’s take a look at some cards. Here are three of the most basic and effective pieces of recursion available in the current Advanced metagame—one each for spells, traps, and monsters.

Magician of Faith has become a near-staple in many decks, from Beatdown to Lockdown and back again, and it’s definitely the hottest source of spell recursion in the current Advanced format. It can help a player activate important and powerful Limited spell cards repeatedly, as well as presenting the option of reusing non-Limited spells. Overall, Magician of Faith is an incredibly versatile card. Spells like Nobleman of Crossout, Smashing Ground, Creature Swap, and others that are powerful but may not warrant two slots in a decklist can be neatly exploited, and its Light attribute makes it doubly useful in Chaos decks.

The biggest advantage to Magician of Faith since the inception of the new Forbidden List (which brought back Delinquent Duo, one of the Magician’s best targets) is Apprentice Magician. The Apprentice can special summon Magician of Faith as well as Hand of Nephthys, Old Vindictive Magician, and even Time Wizard, so it’s already a highly versatile card. Many tournaments in the past few months have featured  Apprentice Magician and Magician of Faith in many ratios, from 1:1 to 2:2 and everything in between. If you’re looking to make good use of recursive mechanics for spell cards, Magician of Faith is your best bet.

Magician of Faith’s trap-based equivalent, Mask of Darkness, is a good choice in decks that like to take advantage of Limited cards, like Ring of Destruction, Mirror Force, or Call of the Haunted. It also works well in Lockdown decks to reinforce the lock, either by bringing back destroyed copies of Gravity Bind or allowing you to reuse cards like Solemn Judgment that help protect your locking agents on the field.

The important thing to remember about Mask of Darkness is that while it does offer the raw card advantage also given by Magician of Faith, it draws on a smaller and more refined card pool. Magician of Faith will have about fifteen possible cards to recur in an average deck, but Mask of Darkness is likely to have only four to six possible cards to recur. This will change how you regard it, not only in a “Do I want to play this card?” sense, but also how you actually play it. Magician of Faith will likely have something to return from the graveyard by turn 2, but Mask of Darkness will require some restraint. Though it takes some skill and is a bit more difficult to play, Mask of Darkness can be a powerful card and it definitely ranks among the top underrated monsters in most current metagames.

Monster Reincarnation

This spell has seen serious use lately in the decks of some top-level players. While it might appear to provide an underwhelming two-for-one card disadvantage at first, there’s a lot to consider when evaluating this card’s effectiveness.

Check out Sinister Serpent and Night Assailant, both of which can essentially negate the cost of Monster Reincarnation. When Reincarnaton is just a one-for-one trade, trading itself for a monster of your choice, it’s easy to see it as a pretty good deal. This means it won’t be easy to use until the mid-game, but that’s all right. You probably won’t have many monsters you want back from the graveyard until turn 5, anyway.

There are lots of great non-Limited monsters that you may want to reuse: Kycoo the Ghost Destroyer, D. D. Assailant, Zombyra the Dark, Mystic Tomato, Apprentice Magician, and Magician of Faith are all good examples. There are plenty of other monsters that can be useful in multiples in certain deck types, but may not warrant a second or third copy in an individual deck. Monster Reincarnation can also become a great way to cycle through monsters you don’t currently need. It’s a strong piece of risk management in decks running three or more tribute monsters, and while other cards also have worthwhile discard costs, this one is constructive instead of destructive. That makes it a rarity.

There are lots of other good recursion cards available to Advanced duelists. Cards like The Warrior Returning Alive and Backup Soldier can be valuable in the correct decks, and the latter is highly underappreciated—a trap card that can give a three-for-one trade in hand advantage? Sure, you need to build a deck around normal monsters, but doing so could turn out to be worth it once you consider the numbers.

Recursion has always been an important element of Yu-Gi-Oh!, and we’re currently experiencing metagames that have made recursion more important than at any other period in the game’s history. Understanding the basic math behind recursive strategies (and some options like the ones we’ve looked at today) will help you get an edge over other competitors. If you’re not currently using any recursion, you’re long overdue. Go ahead and give it a try—you’ll be surprised at the versatility and power of recursive mechanics.