Limited is essentially about two things: card advantage and tempo. Card advantage is an easy concept to understand—it's about who has more cards, using a single card to generate two or three, and understanding that it is inherently a bad thing when you have to use two cards to be rid of one. Tempo is a much trickier beast. Tempo is the pace of the game. It's about who is leading and who is the aggressor, and it might be better defined as who has mana untapped when the action is going on.
The other way tempo can lead to more cards for you is when you've come out of the gates racing and have dropped him to a very low life total early. He will now have fewer options (because he has less time with which to act) and will often be forced to make what would otherwise be bad blocks and use good removal on otherwise bad creatures to stay alive and stabilise. If he is on 6 life and you have a Shade of Trokair that is able to become a 6/7 each turn, then unless he can kill it with all of his men, he will be forced to chump block it every turn until he finds an answer or dies.
There can be times when card advantage can be less important than tempo. If a game is blisteringly fast, it might be best to not suspend a Nantuko Shaman so you can block or attack a turn earlier. You might not have enough time to get to your expensive removal spell to deal with a threat and be forced to double block it. The other case is when you have pulled far ahead on cards, thanks to say a Candles of Leng, and although you could continue to pull further ahead, your mana would be better spent playing all of your freshly drawn spells to create a dominating board position (tempo) so as to win the game now before he can either come back or rip his game winning spell.
Understanding tempo is a tricky process, one which varies from format to format, and is another one of those things that can only be understood through playing a format a lot. I was playing an IPA tournament on Magic Online the other day, and had forgotten how viscously single cards could cause game-winning tempo swings—cards like Magma Burst, Rushing River, and Jilt, which although inherently good because they provide two-for-ones, also set one player dramatically back in board position for a relatively cheap cost, effectively sealing them out of the game in many cases. Things have changed a lot since those days, and it is unusual to find cards of such game-swinging power in the common and (sometimes) uncommon slots. Wizards have learned a thing or two from the past, and it is now a rare thing to find cards that will so drastically affect the tempo of a game.
I will take a stand and say that I view Limited much more from a card advantage perspective than a tempo one. I, as I have explained, often understand the importance of tempo in so far as it affects card advantage. This is not to say that I do not recognise that tempo plays an important role, but that I believe Limited to be fundamentally about card advantage more than anything else.
Some cards are purely tempo-based, like Groundbreaker, and others are mainly good because they cause such a huge tempo shift, cards like Riftwing Cloudskate and Temporal Eddy, although it should be noted that these last two are good because they provide semi-removal effects on top of providing a body or the loss of a draw step (one-for-ones, with a bit of bounce on the side—semi card advantage). But most cards are good because they provide card advantage, have evasion, have repeatable effects, are removal, or are fat.
Fatties are next up under the microscope. Fatties' strength lies in them being so big that they will almost never trade with an opponent's creature, and it will take several of them to take them down. Their disadvantage is that they tend to cost a helluva lot of mana. Often this will render them seldom playable or restrict you to only playing one per deck, as their impact may never be felt because you might not reach that much mana, and if you draw multiples you will often die with them in your grip. This means that things that cost 7+ will tend to be limited to just one, and six-cost guys shouldn't really amount to more than three. These, as always, are guidelines and can sometimes be broken.
The other major limiting factor of boombooms is that, although they will trade advantageously with other creatures, they tend to trade one for one with the good removal spells. Sure, you'll dodge a lot of the conditional removal, but a Scaled Wurm dies just as easily to a Dark Banishing as a Goblin Raider does.
A format with lots of early drops and tempo-oriented cards limits the number of fatties you can play. However, if, like Ninth Edition, there is a lack of early drops or efficient ways to win a game quickly, then you can get a little more liberal with your big guys, especially if you have a lot of acceleration. One of my favourite draft archetypes back in Mirrodin block revolved around picked up multiple Dawn's Reflections and then playing massive fatties turn after turn. The same can be achieved in Time Spiral with Mwonvuli Acid-Mosses and Hunting Wilds, although it is not as effective because the quality of fat isn't too high.
Removal also tends to be one of the few ways to deal with 'bombs' and 'evasion' creatures—read on. People often ask me why removal gets picked higher than a great creature. This is because removal is far scarcer than are good targets for it. It is easy to build a deck that will overload your opponent's removal by having too many fatties, bombs, creatures with repeated effects, and evasion creatures to kill than he has ways of killing them.
Combat tricks, normally pump spells, are good for the same reason as removal when it comes to tempo. You can remove a blocker for a cheap cost and then lay another attacker for next turn, whilst they are left with a radically depleted board position. Conditional removal such as burn and Strangling Soot can be foiled by pump spells, meaning that not only do combat tricks increase you tempo, they help protect your men too.
They also enable you to take down fatties, but this will often leave you vulnerable to an instant speed removal two-for-one-ing you, by removing your blocker, and the combat trick, before damage is assigned. In order to prevent this, it is normally better to double block to induce their removal spell (if it is conditional, then you can 'counter' it with your pump). If none is forthcoming, you can stack damage and then save the better of your two guys if both were assigned lethal damage, or both if not. If you are using a trick to save your guy in a trade of equals, still assign damage first so that removal won't ruin you.
It is all to easy to clog up the combat step with a myriad of vanilla guys who stare down at each other and throw insults about but can never quite make it into the red zone. This is where creatures with evasion come in. Be it flying, fear, or landwalking, if they can't be blocked then their value increases. Flyers also increase in value because they can block other flyers. Even if the board is not clogged up (as it shouldn't be if you play well), if you have an evasion creature attacking, when it nears being lethal, you can just chump your way to victory whilst he keeps swinging unimpeded. As there are few ways to dealing with evasion creatures, due to their very nature, another reason to play removal is to eliminate them.
Cards with repeatable effects normally fall into three categories—they ping, pump or heal. The classic pinger recently brought back in fashion is Prodigal Sorcerer. When he is on the board, his pseudo-effect is that all your opponent's one toughness creatures are as good as dead and all of your creatures, when involved in combat, have one more power—not to mention how this effect doubles if you get a second pinger or Scryb Rangers.
I've been playing a long time, and I'm not entirely sure what the archetypical pumper is. There are some from way back when, but they tended to be before Limited was played, so I'll provide the selection of Timberwatch Elf, Nantuko Disciple, and Kabuto Moth. Healers, like Hallowed Healer, tend to perform a similar duty, though they effectively only pump toughness. Their difference is that they can prevent damage to players, so they can defend against burn and evasion creatures. Both types of cards jam up your opponent's combat step and liberate your own.
Repeatable effects aren't just limited to creatures. Candles of Leng and Treasure Trove are examples that draw cards. Serrated Arrows and Pyrohemia deal with creatures. The list is nigh-on endless, but you catch my drift. The residual effects these cards have on the game as well as the flat-out card advantage they can often generate are why repeatable effects are so strong.
The other type of bomb is, funnily enough, the non-creature. Damnation, Verdant Embrace, Sulfurous Blast, Pyrohemia, Stroke of Genius, etc. Once again, these do absurd things, almost always either inherently linked to generating massive card advantage or killing many creatures or simply being ridiculously powerful. These are much harder to play around for your opponents and, sometimes, a little more difficult to play correctly. Either way, they stand out, often because of a little gold symbol to the right of the card, but more often than not because they do something massively unfair.
These are the base qualities of cards that tend to make them good in Limited. Many cards possess multiple traits—for example, Twinstrike is both removal and card advantage. In fact, most cards fall into the card advantage category, which is the main reason why they are considered good to start with.
Conversely, there are cards which are inherently bad. These tend, simply enough, to be cards that generate negative card advantage. Cards like Delirium Skeins and One with Nothing are obvious examples. Lava Spike might have a tempo effect on the game, but after it's resolved you have one card less and the effect was pretty pointless—might as well Brute Force an unblocked Greenseeker on turn two! Creatures that have next to no impact on the game also fall into this category, because it is almost impossible for them to trade with another creature—cards like Mindlash Sliver and Children of Korlis.
Auras that enchant creatures have always fallen into this category. They get attached to a guy, make him better, and then stick a really big target on his forehead, begging to be destroyed. You are offering, much like many annoying shop window adverts, a two-for-one at the bargain price of next to nothing. Some creature-attaching Auras have had some success lately, like Maniacal Rage and Griffin Guide, because they pay for themselves when the creature dies. Wizards even created Equipment so as to keep the idea of creature enchantments around without offering so much disadvantage.
For now, concentrate on analysing whether a card possesses these attributes, and if you think it is good, you will tend to find that it will possess one or the other. Again, the exception is random dorks, which are okay (and some better than others) but are never the reason to get excited about a deck or the real reason behind the deck's victories.
Ninth Edition draft is a great example of a format almost completely without tempo, where every pick, hopefully, is a card with one of the listed qualities. It is a great lesson in Limited all by itself, and next week I will be bringing you a 999 draft walkthrough, which will show you how important these aspects are.