Yu-Gi-Oh! Theory: The Fundamentals | The Irish Duelist

Yu-Gi-Oh! Theory: The Fundamentals

Afternoon Duelists, today I've picked out another article from the DuelistGroundz forums, this time by MasterSimon. In it he explains what Yu-Gi-Oh! Theory (or Theory-Oh! as we call it over there on DGZ) is, and breaks it down into its core components, take a look:

Yu-Gi-Oh! Theory: The Fundamentals

by MasterSimon

As with any field of study it is important to understand the fundamentals that drive the various interactions and laws governing the system. In Physics this consists of the three fundamental forces: Gravity, Strong Interaction, and Electroweak Interaction. Taking a page from the physics playbook I'll try to understand the fundamentals of Yu-Gi-Oh!

First we need to understand the objective of (competitive) Yu-Gi-Oh! gameplay. In Yu-Gi-Oh!, everything is a resource: Cards in hand, cards in deck, cards in play, cards in graveyard, removed from play cards, cards in extra deck, life points, monster summon, game phases, time, turns, etc. The game is all about managing these resources and using them to deny the same resources to your opponent. To win a game of Yu-Gi-Oh! you must deny your opponent life points (reduce their Life Points to zero) or cards in deck (your opponent cannot draw a card when they are supposed to draw). There are other cards that can change win conditions. For instances, a card like Final Countdown makes turns a resource your opponent can run out of.

The Resources

These resources can be divided into three types if groups:

  • Resources you start with and naturally get more of as the game progresses.

  • Resources you don't start with, but naturally get more of as the game progresses.

  • Resources you start with, but don't get more of naturally or without action.

The first type of resources is playable cards. You start the game with a 5 card hand, and gain an additional card every draw phase. It doesn't matter if the cards are in hand, on the field, in the graveyard, or removed from play. The important thing is their effects can be activated, or they can be moved to a relevant area such as the field.

The second type of resources includes the game phase, normal summons, “Once per turn” effects, and other effects you can activate multiple times. You only get one normal summon per turn and battle phase per turn. Your normal summon is essentially Yu-Gi-Oh!'s version of a land drop (Magic: the Gathering reference).

The third type of resource includes life points and cards in deck. These resources are important because without them you can't play the game. If your life points are reduced to zero or you have no cards left in your deck, you lose the game. These resources measure your ability to continue playing the game.

The Forces:

To coincide with the three types of resources, we have three fundamental forces, that dictate how cards and plays are evaluated in Yu-Gi-Oh!

The three forces are:

  • Card Economy

  • Tempo

  • Stamina

Card economy deals with the first type of resources. It is a spectrum consisting of card advantage on one end and card disadvantage on the other. To gain card advantage you want to attempt to trade your playable cards for your opponent's playable cards. Essentially you are attempting to reduce your opponent's options while increasing yours. Even if your opponent has some cards left in their hand, on the field, or in some other zone, it doesn’t matter if they are not relevant.

Tempo deals with manipulation of the second type of resources. While you may not be getting additional cards for summoning a monster, you do gain some tempo. You could be in a better board position even though you may not technically be in a better card position. Similarly if you deny your opponent the ability to take advantage of their battle phase with a card like threatening roar you are not ahead when it comes to cards, but you may still get some tempo. The important thing about tempo is that it must be converted to card advantage or stamina advantage to get any tangible use out of it. This is most easily done by simply attacking with a monster you summoned, but there are many other ways.

Stamina deals with the manipulation of the third type of resource. Sometimes you'll trade life or cards in deck for an effect. Other times it will be the other way around. This is probably the more important aspect of stamina because it sets it apart from card advantage. Trading a card simply to reduce your opponent's life points doesn't sound appealing from a card advantage standpoint, but that card doesn't matter if your opponent's life points goes to zero.

Card Economy

Card economy incorporates the importance of more options and better options when evaluating cards. This means understanding card advantage, card disadvantage, virtual advantage, and live vs. dead cards.

Card advantage deals with card quantity, it allows us to look at how many cards we are generating. The inherent cost of playing a card is the card itself. The most basic card for understanding the concept of card advantage is Pot of Greed. You play one card, two get two. The important thing about card advantage is it helps us get more options. Having more options gives us different ways to move toward victory. This is why understanding card advantage can be useful. However, understanding card advantage alone is only useful insofar that we assume that indeed every card is equal. When it comes to card economy (and winning games) quantity is not the only thing that matters, quality is very important too.

Card disadvantage is on the opposite end of the spectrum. A mechanical example built into the game is Equip spells. When a Monster that is Equipped with an Equip spell is destroyed, so is the Equip spell. This 2-for-1 makes it hard for Equip spells to be viable. Card disadvantage is not always a problem though. Take a common play from the Lightsworn deck. When you discard a card for Monster Reincarnation or use the effect of Beckoning Light you are indeed serving yourself with card disadvantage. However think about what cards are you getting in return, and what cards you are loosing. If you discarded a card that is life in the graveyard (i.e. Necro Gardna) in exchange for a live Judgment Dragon, you’ve actually gotten more value, as Judgment Dragon is worth both than Monster Reincarnation + Necro Gardna in many cases. This is an example of card economy at work.

What card advantage (and disadvantage) gives us is a very tangible way to understand how you win the game. You can feel and see the cards, so it is pretty easy to physically see the card impact of how you play. However, the gameplay is situational, and thus a card's value changes with the game state. Virtual advantage (or disadvantage) has more to do with manipulating these game states to make sure more of your cards are relevant and less of your opponent’s cards are relevant. An example of a card that allows you do to this is Jinzo. Let's assume your opponent has a trap based deck. Now let's assume you are running Jinzo or Royal Decree and few (other) trap cards. You clearly have an advantage, but this won't show up by simply counting cards. Similarly, Dimensional Fissure and Macro Cosmos help when it comes to gaining an advantage over graveyard based decks.

Virtual advantage goes hand-in-hand with the concept of live and dead cards. A card live when it can make some sort of impact to the game (it can be played/summoned/set, or its effect can be activated). Some cards can actually still be alive when they are in the Graveyard (ex: Necro Gardna, Mezuki). Dead cards are cards that have no impact on the game. A card can be dead in your hand, on the field, in your graveyard, or removed from play. Live cards have varying values depending on their utility in the current game-state. A card is not dead if it can be used for a cost, and even bluffing can squeeze some value out of a card, it just may not have full value as if it was totally alive and relevant. Dead cards are essentially worthless. Since the game state can change very rapidly, a card can become live or dead at various points in a given game or turn. Keeping track of these changes is important to help you make the proper play.

The central axiom of card economy is that the value of a card is relative to the current position in the game. You want to get the most value out of your exchanges. This is a very useful concept when considering when to activate your Bottomless Trap Hole or Dimensional Prison. You are essentially trading one of your cards for one of theirs, but how much value you are actually getting out of the exchange?


Considering how many people have the knowledge that Tempo exists and how strongly it affects the game, it is very surprising how misunderstood it is. When it comes to Yu-Gi-Oh! there is very little literature devoted to it, and much of it is very wrong. Jason Grabher-Meyer wrote an article on TCG player that attempted to paint tempo simply as game speed and measure it by means of cards lost per turn. The problem with this theory is that cards like The Cheerful Coffin will cause me to lose cards, but I won't necessarily gain any tempo. Sure the game may end faster, but that is because I will probably lose due to the lack of card advantage.

Instead of thinking of tempo simply as speed we need to think of it more in terms of rhythm. How do you measure the rhythm of the duel? Think about music. In music tempo is measured in beats per minute. What are the "beats" of a duel? Well there are certain resources that you naturally gain access to as the game progresses. The resources related to tempo are: Summoning Monsters, Game Phases, Reusable Effects, and Card Velocity. Tempo is very much about gaining access to resources you wouldn’t normally have. Unlike card advantage, tempo must be taken advantage or it simply disappears.

Under normal game conditions you can only normal summon or set one most per turn. This is similar to the land drop in Magic: the Gathering. The major difference between the two is how many times we are allowed to break the rule. There are two ways in which we gain tempo from our monster summons: quality and quantity. Summoning an efficient monster (like a Level 4 or lower 1900 ATK monster with no drawback) gains you tempo based on the quality of a monster. Thunder King Rai-Oh for instance is both an efficient monster, and can be exchanged to stop your opponent from special summoning. Thunder King Rai-Oh is a pure tempo play. It lets you gain tempo, and prevent your opponent from gaining tempo. Oddly enough Thunder King Rai-Oh is used in a deck that is seen as being "slow" when it comes to the speed of the game. It does help in slowing your opponent's deck down, but it is very helpful in speeding your game up. Beating your opponent in the face for at least 1900 damage every battle phase adds up pretty quickly. Summoning multiple monsters per turn can also give you tempo advantage. If the natural rate of summoning is 1 monster per turn, then summoning multiple monsters per turn puts you above this natural rate. Double Summon gives you an additional normal summon this turn. This allows you to be up 2 to 1. Another way to achieve a 2 summon to 1 outcome is to prevent your opponents summoning with cards like Trap Hole or Bottomless Trap Hole. Stopping your opponent from summoning goes a long way to preventing them from gaining tempo. Quality and quantity don't have to be mutually exclusive – some decks can summon multiple high quality Synchro monsters in a single turn – but some cards like Scapegoat give us multiple low quality bodies in exchange for not being able to summon anything else the turn it is activated.

All phases can have tempo squeezed out of them with the help of card effects. The Draw phase has cards like Destiny Hero – Dasher and Heart of the Underdog. The Standby phase has cards like Treeborn Frog and Dark Snake Syndrome. The end phase has cards like Brain Crusher and XX-Saber Darksoul. The thing about the Battle phase that sets it apart form the others is that it has natural mechanisms to generate tempo. Attacking is the only action in the game that can generate card advantage, tempo advantage, and stamina advantage simultaneously. It does so by denying your opponent cards, field presence, and life points. Tempo and card advantage are related by monster presence. Tempo and stamina are related at the rate in which you can push to finish the game. By winning battles you reduce your opponent's ability to use their monsters to put pressure on you, and you bring yourself closer to reducing their life points to zero. Denying your opponent tempo trough the battle phase can also be very important. If they cannot use their battle phase effectively they won't be able to apply pressure on you. This can be accomplished with cards like: Spirit Reaper, Battle Fader, Threatening Roar, Magic Cylinder, Dimensional Prison, Book of Moon, Enemy Controller, and more.

When it comes to the idea of having access to cards you wouldn’t normally have access too you need look no further than the concept of card velocity. Card velocity examines the speed at which cards are moving from the deck to other relevant places. Foolish Burial is card disadvantage on the surface, but it is card velocity through and through. It can give you access to your Treeborn Frog, Fishborg blaster, Dandylion, Glow-Up Bulb, etc. Self-milling and tutors (cards that allow you to search a card from your deck) have a similar effect. The effect of card velocity is two fold. Firstly, you are gaining access to a card you don’t have access to yet, secondly you are gaining at least one draw phase as your deck is a card (or more) smaller. Using an effect like Swap Frog to get Treeborn Frog to the graveyard is a huge tempo push. Treeborn Frog in an extra summon a turn, allows you easier access to tribute monsters, and is card advantage to boot. On top of that you no longer have to worry about drawing that Treeborn Frog and increase your chances of drawing a card that can take advantage of Treeborn. Similarly Shien’s Smoke Signal and Reinforcement of the Army allow you access to Legendary Six Samurai – Kageki which you can use to special summon Kagemusha of the Six Samurai and have early access to Legendary Six Samurai - Shi En on turn one. All of this was done trough tempo, not card advantage. When it comes to gaining tempo the important question to ask yourself is, what can I do with it?


Stamina is the name I've given a concept dubbed "The Philosophy of Fire" by Magic the Gathering player and writer Michael Flores. As a concept it has been pretty much absent from the minds of Yu-Gi-Oh! Players, but been put into practice many times to produce some of the fastest decks we've seen. Many FTK decks run on this concept: Frogs, Chimeratech Overdragon, Magical Scientist, Dark Magician of Chaos, Exchange of the Spirit, Empty Jar, Reversal Quiz, etc.

Stamina deals with resources that measure a players’ ability to continue to play the game. These are resources which players start the game with, but don't naturally gain over the course of the duel. This includes things like life points, and cards in deck. Early game, while Stamina is high for both players, cards that interact negatively with your opponent's stamina or positively with your stamina are worth less because the resources are already abundant. Naturally over the course of the game, cards are lost from the deck. Life points can be lose as well, but this requires action from the players. Later in the game, when cards in deck and life points are low, stamina related effects are valuable. A Single card or attack can end the game. This means early game, cards must be able to deal a lot of damage or mill many cards for your opponent's deck to be useful. When thinking about using your stamina the question to ask yourself is, how will this affect me later in the game?

For burn cards you'll want to be using your Magical Cylinders or Dimension Walls when your opponent's stronger monsters attack. Other options are Des Koala and Secret Barrel since early game your opponent will have a larger hand and more cards overall, so they should be able to do some decent damage. Another would be Chain Strike at Chan Link 4 or 5. Another way to go would be to use Just Desserts and Ojama Trio is get in at least 1500 damage and clog your opponent's field to prevent them from swarming you. At the core of these examples is an underlying theme: Burn damage must be close to baseline monster damage (1500+) early game in order to stay in the race. Another viable option is to use cards that can continuously apply pressure on their life points. In a way this gives you both tempo and stamina advantage. Some cards that do this are: Stealth Bird, Solar Flare Dragon, Dark Snake Syndrome, and Lava Golem + Nightmare Wheel. Wave-Motion Cannon can create a similar situation, but it can be removed form the field before the effect can be actualized. Later in the game weaker burn cards like Poison of the Old Man and Tremendous Fire may be useful in finishing off any remaining life points. If you are running a deck totally dedicated to burn it might not matter when you play them though, but it should be noted that the lose of card advantage early game without a big reward in damage may give your opponent the edge. Don't forget you can interact with Stamina simply by doing battle damage to your opponent, so if you run a stamina related card it better be worth it. Attacking is the most efficient way to lower your opponent's stamina as it costs you no cards to deal damage, and can be done one per turn by each monster you control.

For milling cards the same rule applies. You want your speed to match that of a creature based deck. If you are not planning on running disruption you may need to be even faster. Cards like Morphing Jar, Morphing Jar #2, Necroface are more useful early game than Hand Destruction, Dark World Dealing, or other lesser cards. Card Destruction + Serial Spell is another interesting finishing strategy for mill decks and in combination with Morphing Jar can be at least 15 cards out of the deck (more with Book of Moon/Book of Eclipse/Book of Taiyou shenanigans).

When it comes to using Stamina as a cost there is no shortage of playable card that allow you to exchange survivability for effects. Solemn Warning and Solemn Judgment are examples seen in many decks. The opposite rule applies to using stamina as a cost. Early game, the cost isn’t actually worth all that much, since you still have a large number of life points and cards in deck at your disposal. Determining when to pay such costs comes down to understanding how it will affect your overall survivability. With Solemn Warning if you are trading 2000 LP and a card for more than 2000 damage that is an easy call to make. Another reason you may choose to pull the trigger is if the result summon would result in a huge swing in tempo or card advantage. Card velocity also plays a role when self-milling. So when it comes to self-milling the upsides can outweigh the downsides rather easily. Just make sure your deck wants to use such methods over pin-point cad velocity generators.


To review the main themes of all these concepts:

  • Card economy focuses on using your resources to give yourself more and better options than your opponent.

  • Tempo focuses on using your resources to put yourself in a better position than your opponent.

  • Stamina focuses on using your resources to remove your opponent's ability to continue to play the game.

The main questions to ask when deciding what plays to make:
  • How much value am I getting out of my card(s)?

  • What can I do with this tempo?

  • What effect will this have later in the game?

Hopefully you can use these theories to help you evaluate cards, construct better decks, and make better play decisions.