However, suppose we each have three 1/1s, three 2/2s, two 3/3s, two 4/4s and a 5/5 in addition to those big creatures. At this point it becomes all but impossible to make an effective attack. My 2/2s will block your 1/1s, my 3/3s will block your 2/2s and so on up the line. Even a single 1/1 on each side can make a good attack into a bad attack: Suddenly that 5/6 is teaming up with a 1/1 to kill your 6/6. The more creatures we each have and the more scrambled their power, toughness and abilities the greater the chance that I have an effective way to block. I'll use creatures just big enough to win combats on the creatures I want to kill and then either take the damage or chump block the remaining threats.
As the board becomes complicated, it favors the defender. The attacker gains a lot more possible attacks, but the defender's options multiply even faster. After a while it becomes impossible to profitably attack with a vanilla creature. Attack with a 4/4 and I'll block with two 2/4s or a 5/5. Attack with a 2/4 and I'll block with a 4/4. Attack with a 7/5 and I'll throw a 5/4 in the way. At some point the only option becomes an Alpha Strike where I turn all my creatures or all my worthwhile potential attackers sideways at the same time to hope that you run out of good blockers. That only becomes possible when I have an overall advantage: Either I have more creatures than you do, I have so much more power on the table that you will run out of good blocks or I have a trick or combination of tricks that can turn the battle around. When that doesn't happen, only creatures with evasion or other relevant abilities ever get to attack.
Under normal circumstances a complicated board favors the defender. Smaller creatures go dead as potential attackers other than as part of an Alpha Strike, but smaller defenders can often be combined with other defenders to create a profitable block. Whenever you play an aggressive deck in limited or in a constructed battle between two creature decks the threat of this overcomplicated type of board position is always there. You're on a treadmill. Each time that you both get a creature it gets harder to attack, so you need to press your attack while you still can, using the threat of damage to force your opponent to trade off his creatures. If you drafted creatures with good power, most of the time that threat is enough to make him fall in line and block.
The other reason that a player who wants to attack might want to leave comparable creatures on both sides of the board is that there are cards that reward him for doing so. Most prominent are cards in the mold of Falter or Overrun, both of which have become stand-ins for all cards that share the same purpose – cards are referred to as 'this set's Falter' or 'this block's Overrun.' You can also have cards like Glorious Anthem or Ursapine that make all your other creatures better. In these cases, you're creating a future situation where your 2/2 is more valuable than his 2/2: Yours gets to attack and his won't get to block, or when the time comes yours will be a 5/5. These cards can be in your hand or they can be in your deck waiting to be drawn later in the game. Either way they can form part of a plan. This ends up being similar to the unequal creature scenario, which I'll deal with in the next section.
The primary reason that a deck that intends to remain defensive on the ground wants to trade off equal creatures is that it defends against future spells. When the board is empty, you're in little danger. When the board is full, attacking becomes difficult but you could also lose outright at any time to the wrong spell. So could your opponent, but most of the time you know that you don't have the right spell in your deck to make him pay, so you're adjusting your plan accordingly. For that reason, you don't want to complicate the board more than necessary even if you have no intention of turning the ground around and attacking him there later in the game. Once things are stalled, each extra point of power you give him adds to the potential for trouble. That is another big reason for trades. Both players know that they don't have the right cards to take advantage of a stalled board, but both fear that their opponent might. One player attacks to force the trade, and the other welcomes the trade thanks to asymmetrical information. Often a defensive deck plays creatures with the express intent of trading them off to buy time for its more powerful late game spells.
Unequal Creatures, Unequal Futures
Either way, this can provide a powerful incentive to trade creatures or avoid trading them; no one wants to trade down if they have a choice, but you need to be wary of taking this too far. For example, take Stonewood Invoker. Just don't take it too far. If both players survive enough turns to put eight lands on the table Stonewood Invoker can dominate the entire game. As a result, often players would avoid trading off Stonewood Invoker for other two drops. The problem is that a creature you're not afraid to trade is a lot better than a creature you can't afford to risk. The Invoker refuses to block an opposing 2/2 and then refuses to attack into another, confident that it is 'more valuable.' The problem is that a lot of that value comes from the fact that it also has all the strengths of a vanilla 2/2. If you give them up, you end up with a worse card than if you never had that extra ability in the first place.
When you're considering the value of a creature, remember to devalue it on this basis if you start to consider it too valuable to lose. A modern example of the same phenomenon would be the Guildmages. A player who has drafted Dimir Guildmage has two powerful abilities at his disposal, but often he ends up giving up what would otherwise be an efficiently priced creature because its other abilities are too valuable; give it a chance to attack or block safely and it will, but the other player knows you won't risk losing your card drawing and discard engines.
Unequal Removal, Unequal Targets
Another common consideration when trading is the removal content of both decks, especially in constructed. If a deck is removal heavy, it risks drawing too many removal spells for not enough good targets. You don't want to trade off your only creature and be left holding multiple removal spells when you could be attacking instead, giving your opponent time to take that removal out of your hand or draw more business spells to get back in the game. This is most important if your deck might actually have almost as many removal spells as your opponent has creatures, but that can happen based on unusual draws. Seek to protect what you don't have in abundance and make good use of what you do have in abundance.
There's also the danger of playing against mass removal. If your opponent is packing Pyroclasm, for example, then every creature you have in play that Pyroclasm would kill becomes a potential liability, reducing your ability to play other creatures that Pyroclasm could kill. You might happily trade a 3/1 off for a 1/3 because that lets you play a new creature out of your hand without walking into a trap. Repeatable mass removal is the biggest risk of all. If your opponent has a “pinger” in his deck like Viashino Fangtail then trading off your one toughness creatures helps protects you from a potential future disaster that can be even worse than a Pyroclasm.
Unequal Decks, Unequal Futures
If my deck's cards are more powerful than those in yours, for example if I have six drops where you have two drops, then I will be happy to trade off all our three through five drops and leave my 5/5 facing your 2/2. In fact, I'll even be willing to make a series of completely unfair trades. I'll trade my 4/3 for your 3/2, my 5/4 for your 4/3 and my 6/5 for your 5/4 because that leaves my 7/6 facing your 2/1. Many times, my deck has chosen to trade time for additional resources, so I can afford to give back resources to buy time confident that I still have my long term material advantage. Powerful draft decks often willingly trade off creatures as well as other cards in the early game because they know that if they don't lose early then their deck will carry them to a win later on.
Greetings Fellow Wizard, Do You Wish To Trade?
Like most Magic questions, the decision on whether you are willing to trade off your creatures for his comes down to the same question: Will this trade increase my chances of winning the game? It doesn't matter if the trade is fair, whatever fair means. All that matters is what will happen to the game afterwards. If all you need to do is survive, you might sideboard cards in for the express purpose of trading them. At other times you'll intentionally avoid trading.
No single article could hope to cover this whole topic, but I hope I've given you food for thought, and I encourage you to send in situations of yours where you had to decide whether or not to trade or offer a trade. I'll try to cover one of those next week. In the meantime, please take a moment to let us know what you thought of this approach (either this article in particular, or the interlude structure as a whole) on the message boards.