Longwei's knowledge.

[Sora]

This lesson is with regards to basic deck building, the key element in dueling once you know your rules. Listen up Plebe's because it's an important class.

Deck Guidelines
1. Stick to the 40 card minimum. Well, 41 or 42 is ok. But this is the number one mistake that new deckbuilders make. Many newer players believe that by adding more cards they have more options. In fact, the opposite is true: you have less options. Why? When you're dueling, every single card you draw counts. If you can't draw the right card at the right time, you'll lose. The fewer cards you have in your deck, the greater your chances of drawing the right card. Let's say it's deep into the duel. Both players have gone through a lot of cards and now it's down to a topdecking war. Who has a greater chance of drawing the card they need, the player with 5 cards left or the player with 25 cards left? Some decks also run best with 3 Upstart Goblin effectively making the deck count 37.

2. Don't try to do too many things at once. Pick one central idea and choose every card based on that idea. If a card does not blend well with your central strategy, or is counterintuitive, avoid it. There's probably a better choice. Don't mix ideas unless they actually benefit from each other. For example, there's no benefit from mixing Gladiator Beasts and Lightsworns. GBs rely on having cards in the deck, while Lightsworns mill cards out of the deck. Lightsworns rely on explosive finishing moves while GBs are much slower-paced. Some hybrids are beneficial, though. For example, Lightsworns and DARK Monsters; DARK decks thrive on having monsters in the Graveyard, and using LIGHTs and DARKs together allows the use of Black Luster Soldier - Envoy of the Beginning and Chaos Sorcerer.

3. Monsters are not win conditions. Continuing on the idea of number 2, your central theme should not be "Summon this monster". Aside from Exodia, there is no monster that will outright win you the game. Not the Egyptian Gods, not the Sacred Beasts, not the Aesirs, not Dark Armed Dragon, not Judgment Dragon, not anyone. Monsters, even incredibly powerful monsters, are tools to be used at your disposal. They are not win conditions.

4. Anything worth running is worth running in multiples. This is more true of monsters than spells and traps, but is in general true. Most top decks run all cards that aren't limited in twos or threes. The logic is this: if a card is powerful, you want to draw it more often. If you have more copies, you'll do that.

5. The less conditional a card is the better. This covers activation conditions, costs, benefits, card advantage, everything. The best card is one that is powerful, has little to no cost, generates lots of card advantage, and requires no other cards to be present. Dark Hole is a prime example of such a card. When considering this point, ask yourself "How useful would this card be if it were the only card that I had to use?" or more simply "What would topdecking this card mean for me?"

6. The more versatile a card is, the better. Continuing number 5, a card that can be used against more cards and strategies is more helpful than a card with limited use. For example, Solemn Judgment can be used against all types of cards, making it more useful than Magic Jammer, which can only negate Spells.

7. The more Card Advantage you result in from using a card, the better. To explain this key point, I'll again look at Dark Hole. If the opponent has two monsters, and you have none, activating Dark Hole will leave with the opponent with 2 less cards, and you with only one less card. That generates Card Advantage. Now let's look at the same situation, this time using Lightning Vortex. Lightning Vortex requires a Discard cost, which means it requires 2 cards to play: LV and the discarded card. Your opponent loses 2 cards, and you lose 2 cards. This generates no card advantage.

8. Maintain a proper balance between monsters, spells, and traps. What this means for you depends on the type of deck you're building. Chaos Dragons, for example, rely on milling their monsters to the Graveyard. As a result, they should run more monsters. Gravekeeper's rely on using Spells and Traps to shut down the opponent, so they should run fewer monsters in order to draw more Spells and Traps. Frog Monarchs rely on the effect of Treeborn Frog, so they should run fewer (or no) Traps. To figure out the proper balance, think about what's important in the deck. What does the deck rely on and how should your monster count reflect that? What type of cards would get in the way of your strategy, and what type of cards are crucial to it?

What kind of deck should I make?
Well, that depends on you. Whether you like aggressive Beatdown tactics, slowly Burning your opponent to death, complicated combos, alternate win conditions and watching your opponent await their demise, or controlling your opponent's every move, you should pick a decktype that exhibits those characteristics and matches your playing style. Things to consider when choosing your deck:

Speed: Is my deck capable of swarming the field?

Power: Are the monsters in my deck strong?

Consistency: Can I draw or search the cards I need on a regular basis?

Control: Does my strategy limit my opponent's options?

Explanation of Card Advantage

Pay attention; this is one of the most important concepts in the game.
Card Advantage refers to the number of cards at your disposal, in your hand and on your field. Any time you increase this number, except through your normal draw, that's a +1 in Card Advantage. Any time you decrease your opponent's number while maintaining your own is also a +1. Any time you decrease your own number, or increase your opponent's, that's a -1. Let's look at a few examples:

Example 1: The opponent controls 3 monsters, and you control none. You activate Dark Hole. Because Dark Hole was used up, you have decreased the number of cards at your disposal, resulting in a -1. However, you also forced your opponent to lose 3 cards, which is a +3 for you. By combining your change and your opponent's change, you get the net Card Advantage. In this case, it's +2.

Example 2: Your opponent controls one monster, and you control two. You summon an additional monster from your hand, and your opponent activates Torrential Tribute. Your opponent loses Torrential Tribute and the monster, resulting in a +2 for you, since the opponent now has 2 less cards. You also lose three monsters, resulting in a -3 for you. The resulting card advantage for you is -1.

Example 3: You normal summon The Agent of Mystery - Earth, adding The Agent of Creation - Venus from your Deck to your hand. You now have one more card, resulting in a +1.

Example 4: You activate Mystical Space Typhoon, destroying an opponent's Spell/Trap card. You each lose a card, resulting in no change in Card Advantage.
By learning how to understand and manipulate Card Advantage, you can turn the odds overwhelmingly in your favor. In most situations, the player with 10 cards at his disposal will almost always beat the player with only 3 cards.
Additional reading on Card Advantage: Card Presence and Card Advantage by Jason Grabher-Meyer

Additional reading on how to manipulate Card Advantage: Simplification by Jason Grabher-Meyer

I highly recommend reading these, as he goes into a lot more detail than I do and does a better job of explaining the importance of these concepts.

Card Choices
Additional Reading on Card Choices: http://yugioh.tcgplayer.com/db/article.asp?ID=2272 Utility by Jason Grabher-Meyer]

Again, I highly recommend reading this. He goes into great detail about why certain cards are good and others are not, and will also teach you how to judge the cards for yourself. He does an excellent job of explaining it, much better than I could do, which is why I am referring you to his articles.

Monsters

When choosing the monsters for your deck, think about their effects and how
you can use it to:

Support your strategy.
Gain Card Advantage.
Overwhelm the opponent.
Disrupt the opponent's strategy.
If you look at popular monster choices in the past, you'll see that most of them fit one or more of these categories. I'll discuss each of them in order. Wind-Up Shark can be Special Summoned when you summon a Wind-Up Monsters, supporting the theme of swarming the field for quick Xyz Summons. Sangan is a popular choice as a Floater, because when it's sent to the Graveyard, it generates card advantage by adding another card to your hand. Red-Eyes Darkness Metal Dragon is used to swarm the field and put pressure on the opponent, since they're facing down many big monsters. Thunder King Rai-Oh is a popular choice because it disrupts the opponent's strategy by blocking add-to-hand effects and can negate an inherent Special Summon.

Other things to look at in a monster are: Level, ATK, DEF, and potential combos. Monsters that are level 5 or above are weakened because they require one or more Tributes to summon. ATK and DEF are no-brainers; battling is one of the simplest and most effective ways to control the field. Potential combos allow for greater use of cards that weren't as useful before. For example, Rescue Rabbit summons two level 4 or lower Normal monsters from your deck, but destroys them in the End Phase. This by itself isn't very useful, but if you Xyz Summon with them, you can avoid the destruction drawback and put a big Monster on the field. This is especially useful if you use it to summon an Xyz Monster with a good effect, like Evolzar Laggia.

Spells
When choosing your Spells, think carefully about what you can gain from them:

Draw Power
Search Power
Summon Power
Card Advantage
Disrupting the opponent's strategy

Again, looking at popular Spell choices, you'll see that many of these are present. Solar Recharge is a powerful Draw Spell that allows you to speed through your deck. Wind-Up Factory searches out any Wind-Up that is needed. Monster Reborn allows you to summon back any fallen monster, making it extremely powerful and versatile. Dark Hole is useful in generating Card Advantage. Book of Moon and Mystical Space Typhoon are good for disrupting the opponent, stopping their plays before they can make them.
Traps

Traps are largely used to shut down the opponent. Things to look for in a trap card are:

Versatility
Costs and Conditions
Chainability
Card Advantage
Protection
Disruption

We'll once more look at some popular choices. Solemn Judgment is one of the most versatile Traps available. Mirror Force has no cost and generates lots of card advantage. Compulsory Evacuation Device is chainable and can go off at any time, which is also a part of its versatility. Starlight Road stops potentially devastating cards like Heavy Storm, Dark Hole, and Black Rose Dragon as well as netting you a free Stardust Dragon . Torrential Tribute can interrupt your opponent before they're able to Xyz Summon into a more dangerous monster like Evolzar Laggia

Staples

Staples are cards that can be run in any deck. All of these cards are or were on the banlist. Everything is Semi-Limited/Limited/Banned for a reason.

Book of Moon: This card is very versatile. It can protect your own monsters, block an attack, disrupt the opponent, stop Synchro Summons in their tracks, the uses are endless. It plays more like a Trap Card than a Spell Card.

Dark Hole: I talk about this card a lot. Why? Because it's freaking good. No costs, no conditions, and it creates massive card advantage.

Heavy Storm: This card lets you make uninterrupted plays. The ability to do that can be devastating to your opponent.

Mirror Force: See Dark Hole. What's even better is that it leaves your field untouched.

Monster Reborn: Play this card in everything except Gravekeeper's and Macro. Everything. It's one of the most versatile cards in existence.

Mystical Space Typhoon: Same story as Heavy. Getting rid of your opponent's backrow lets you make uninterrupted plays.

Solemn Judgment: The most versatile negation card ever. There's a reason why it's listed under "God says NO" in the player's glossary.

Solemn Warning: The ability to shut down any kind of summon, including the previously unstoppable Gorz, is gamebreaking.

Torrential Tribute: While not quite as versatile as Dark Hole, this card is still incredibly useful.

Wind-Up Zenmaines: Every turn that it protects itself, you can destroy a card. Because of this, players are reluctant to destroy it, so it can buy you a lot of time.

Temtempo the Percussion Djinn: Largely popular as an answer to Zenmaines, it can strip Xyz Materials and incur the negative effects of Monster such as Utopia and Acid Golem.

Leviair the Sea Dragon: Useful in just about any deck that can make it, especially decks such as Agents that banish a lot. Free Card Advantage.

Number 17: Leviathan Dragon: Leviathan Dragon is easy to summon and goes to 2500 right away, and can become 3000 if needed.

Number 30: Acid Golem of Destruction For when Leviathan can't get to 3000 fast enough. Beware of its negative effects.

Maestroke the Symphony Djinn: With a self-protecting effect as well as a Book of Moon-like effect, Maestroke has numerous uses.

Steelswarm Roach: Steelswarm Roach has a rather lackluster ATK score but can negate two inherent Special Summons. It rises and falls in popularity as decks that it can counter become more or less prominent.

Number 39: Utopia Utopia has good ATK and negate attacks, allowing you to build field presence for another Xyz Summon, or buy time to deal with a bigger Monster.

Semi-Staples

Semi-Staples are cards that can be run in just about any deck. There are some decks where they're not as useful. Many of these are on the banlist. Everything is Semi-Limited/Limited/Banned for a reason.

Black Luster Soldier - Envoy of the Beginning: Almost every deck with a significant amount of LIGHT or DARK monsters attempts to fit Black Luster Soldier. It wins games on its own.

Gorz the Emissary of Darkness: Gorz wins games. Unless you find yourself with cards constantly stuck on the field (like Call of the Haunted), run Gorz.

Sangan This card is a semi-universal searcher. Its uses are too numerous to list.

Thunder King Rai-Oh One of the greatest control cards in the game, TKRO is a powerful addition to most decks.

Tour Guide From the Underworld: Tour Guide can Special Summon a Level 3 Fiend from your Hand or Deck - another Tour Guide, a Sangan, or anything else. This can be used for a Xyz Summon, to gain Field Presence, or to get Sangan more consistently.

Neo-Spacian Grand Mole Another fabulous control card, Grand Mole screws over Synchro and Xyz monsters.

Effect Veiler and D.D. Crow are both useful cards to stop your opponent's big plays and force them to waste cards.

Maxx "C" Many decks need a long chain of Special Summons to gain control of the field. Pitching Maxx C lets you draw a lot of cards if they press on or makes them stop in their tracks. Unlike Effect Veiler and D.D. Crow, you can nearly always use this card in a way that will allow you to draw at least one, so it costs no advantage.

Pot of Duality or as I like to call it, Pot of Consistency. This card makes any deck more consistent, but the prevention of Special Summons means it isn't for every deck.

Call of the Haunted A powerful revival card, similar to Monster Reborn but not as versatile.

Compulsory Evacuation Device An extremely versatile disruption card, but not for every deck.

Dimensional Prison Useful for dealing with a number of troublesome monsters.
Tech Cards

Tech Cards are what make a deck unique. Using techs allows a deck to combat other decks effectively or do more than it normally would do. When selecting tech cards:

Negation cards are a good tech if they're one for one or require no loss of card advantage: Fiendish Chain was a popular tech in some formats, while Koa'ki Meiru Doom has been teched into Plant Sychro decks.

The Tech should not interfere with any strategies in the deck unless the deck can proceed without those strategies or win using little more than that card: Thunder
King Rai-Oh and Doomcaliber Knight are perfect examples.

The more you can do with the tech, the better: Cyber Dragon is a powerful
beatstick and can be used in Synchro and Xyz Summons, but it's also a LIGHT monster and you can steal your opponent's Karakuri or Geargia monsters thanks to Chimeratech Fortress Dragon. Likewise Tragoedia not only can be a powerful attacker, but also it can steal monsters, change levels, and serve as a defensive wall.

Protecting your backrow is useful, but only if you run a significant number of backrow cards or Continuous Spells or Traps: Dark Bribe is a good tech in Gravekeeper's or Macro decks, but out of place in a Chaos Dragon deck.
If a card has a maintenance cost, it must be easy for the deck to pay continuously: Koa'ki Meiru Drago is an amazing card but most decks cannot maintain it effectively.

Cards to Avoid
This section will discuss many of the pitfalls that await new deckbuilders. Cards that seem powerful can actually destroy you.

Magical Mallet, Reload, and Card Trader: Yes, it lets you trade cards you don't want for a new hand. But when you think about it, you're only making life easier for your opponent. If you activate all your Mallets and Reloads on your first turn, you've reduced yourself to a single card with which you plan to take on the opponent's six. If anything happens to that card, which it most likely will, you will lose. These cards cost you card advantage for no real benefit. Avoid them at all costs.

Lightning Vortex: Speaking of costs, that's the main reason why this card isn't as good as it seems. Yes, it destroys all your opponent's monsters, but it has a cost, and that means it's outclassed by Dark Hole in every way. It also can't destroy face-down monsters. It's rare that Lightning Vortex will give you card advantage, and is a card that's better off avoided.

Draining Shield and Magic Cylinder: If you're going to stop your opponent's attack, at least take the monster down with your Trap card. These cards cost card advantage in exchange for Life Point advantage, which is a terrible idea. If you play these cards you're going to lose the game.

Pot of Avarice: Unless you can put a ton of monsters in the Graveyard on a consistent basis, avoid this card. If you really want to "recycle" your monsters, play cards that let you Summon them from the Graveyard instead. Pot of Avarice thickens the deck, and unless you're thinning your deck at high speeds, don't play this card. I said before that everything was Semi-Limited/Limited/Banned for a reason, but that only applies to Pot of Avarice in certain decks. It's not for everyone.

All single-use Burn Spells and Traps and Life Point Gaining Spells and Traps Card Advantage: If you're going to give it up, do something more than a few points of damage.

Almost all Equip Spells: Equip Spells are bad. Why? Because if the equipped monster leaves the field, or is flipped face-down, you lose all the Equip cards. That's an inherent minus, something you should always try to avoid. Exceptions to this rule are few and far between.

All ATK/DEF Boosting Field Spells: Unless it has an additional effect as well, don't bother. Just play stronger monsters and don't waste a card playing the field spell.

All Stall Cards: Buying a few turns gives you time to get a few more cards, but your opponent remains in control of the duel and can continue applying pressure and accumulate cards to stop you from reversing the duel. Stalling doesn't help you win, it just makes you lose more slowly.

Deckbuilding Don'ts

Don't feel confined to one Archetype. Just because you're playing a certain archetype doesn't mean you can't include other powerful cards like Neo-Spacian Grand Mole or Tsukuyomi.

Don't pick cards because they'll be helpful if the duel is going in your favor. Pick cards that will be helpful if the duel ISN'T going in your favor.

Don't be stubborn about your card choices. The best way to improve your deck is to share ideas. Be careful not to become stubborn and refuse to try out ideas, because it may turn out that the idea you rejected could have skyrocketed your deck's power. Don't absolutely insist on keeping certain cards and not trying others.

Don't be afraid to experiment. All the best decks are constantly evolving. A deck is never finalized. Keep trying new things, and you may be the one to bring your decktype to the next level.

Don't be put off by Life Point Costs. The only Life Points you should be concerned with losing are your last ones. All the other ones don't matter, because whether you win with 10,000 or 100, you still win.

Don't think that having a lot of Life Points means you win. Nobody ever won just by having a lot of Life Points. As I said before, the only LP that matters is your last one.

Don't pick a card without looking at any other cards. Often times you'll be able to find a stronger, more effective version of the card you're considering using.

Don't make an OTK deck thinking it will be consistent. A consistent OTK deck is the biggest oxymoron ever, right after the George Bush Center of Intelligence. If you DO manage to make a consistent OTK deck, the next banlist will kill it.

Don't make a deck based off of the anime. Anime/Manga duelists are bad, and every one of them would be crushed by a halfway-decent real life player. Their decks have no staples and are loaded with situational cards.
Chance cards are, by nature, unreliable. A Coin Flip or Die Roll deck will be inconsistent. Cards like Snipe Hunter may have great effects but the chance that they are a minus is too much for most decks.

Good Luck Plebe and Happy Huntings, sorry for all the long lessons but I want you all to be the best you can be.