It was a cold and wintry night of the type well known to longtime residents of the New England region of America when the missive was brought to my attention. It was a plain card, emblazoned on one side with the markings requisite for any post that travels internationally and a scant few lines of script scrawled on the other.

"Expect at half past eleven the morning after next a caller, bearing a package unto which you should give the full measure of your attention. -- S.A.C.D."

Further inspection of the card providing no relevant details, I set the matter aside for the time being.

At the prescribed time an authoritative knock upon my door abruptly reminded me of the mystery afoot. Imagine my surprise when my promised caller turned out to be a uniformed employee of the postal service requesting my signature in acknowledgement of receipt of a package. The package itself was remarkable only in how unremarkable it was: a brown cardboard affair of standard package size, of the type that serves as the model for package illustrations. My dampened excitement notwithstanding, I proceeded to open the parcel and inspect the contents.

Inside, I found a dusty manuscript, the authenticity of which I cannot verify. The author claims to be the great Sherlock Holmes, writing in his retirement years after the conclusion of his career as a consulting detective. Of particular note to me was the fact that the great detective had apparently discovered Magic: The Gathering in his golden years. It was with great interest that I perused the manuscript, and that interest turned to Fascination as I carefully leafed through the pages. Authentic or not, these words deserve to be shared. To that end I have appended a portion of the manuscript to this explanatory note. I hope you find it as interesting and edifying as I did.

Yours in scholarship,

From Chapter One: Introduction and Explanations

It was with great delight that I sat down with a young admirer of my career to learn the game she excitedly referred to as "Magic." She came in response to an ad I circulated in the Post seeking stimulating mental activity. The curse of old age had deteriorated my health to the point that neither crime solving nor chemical solutions, the two pursuits that had aided me in my prime, were of any use to me anymore in overcoming the all-consuming ennui that has plagued me throughout my existence. The same afflictions that had rendered my body little more than a husk had somehow left my faculties unharmed, and I was in dire need of mental stimulation.

Fame is not without its uses, and I had no shortage of guests with ideas for activities to interest me. Watson would have laughed to see 221B once again constantly filled with a steady stream of hopeful visitors in the sitting room, but I was the client now, and none of these consultations left me with hope for a brighter future. Indeed, I was all but resigned to never again feel the rush of a truly interesting problem when Magic: The Gathering entered my life.

Immediately I became fascinated with the game. The problems it presented were as interesting as they were varied, and I quickly recognized that with Magic, I had finally found something that could occupy the rest of my life. I found that playing Magic taxed the deductive abilities I had worked so hard to hone my entire life to the same extent that my work as a consulting detective used to. The world knows about my contributions to detective work through the chronicles written by Dr. Watson, which I have bestowed with the eminently fitting title of "Applications of The Science of Deduction." Watson isn't here to chronicle my adventures in Magic, so I shall have to do it myself. In these pages I seek to elucidate "Further Applications of the Science of Deduction," how the kind of deductive reasoning I pioneered in detective work is also uniquely useful in games of Magic.

From Chapter One: The Exclusion of the Impossible

Is the last card in their hand a game-winning threat or just another removal spell? Games of Magic often hinge on being able to figure out the answer to simple questions like this one, but there is no accurate test for determining the answer. Instead, the player has to make do with whatever shreds of information they can gain via observation and deduction. The science of deduction is hardly something that can be taught, but I shall give it a good try. The fundamental principle of deduction is a remark of mine that is absolutely littered throughout the chronicles of Dr. Watson: "When you have excluded the impossible, whatever remains, however improbable, must be the truth."

The trick to implementing this maxim within a game of Magic is properly discerning what is truly impossible and what is merely improbable. It is tricky in Magic, as almost nothing is truly impossible. Instead, the definition must be extended to the reasonably impossible. Extending my maxim in this way is very rewarding, as a true student of Magic can then use it to, from just the fall of the first few cards, reduce the potential cards in their opponent's deck from thousands to mere tens. A master can do the same for the cards in their opponent's hand. But it is not just the cards that do the talking -- it is pivotally important to understand your opponent. The same card sequences that tell me my skilled opponent is holding a removal spell tell me that my unskilled opponent does not have one, or vice versa. Reasonably impossible is all about the intersection of what your opponent thinks about the game and the cards that they have played.

One of the unique aspects of the game of Magic that draws me to it is the fact that the variance inherent in the game means that sometimes even someone with my prodigious mind finds themselves among the vanquished. The simple fact that there is no way to beat some potential holdings of the opponent means that it is at times correct to determine what the impossible is by what you can't beat, and not by what they can't have. Then our deductions are predicated on the game being winnable, and the results of said deductions help us win if the game can be won. In so doing, our victory certainly becomes the improbable, but improbable is not impossible.

From Chapter Two: The Incident of the Dog in The Night Time

With the passage of time, history most fondly remembers the more atypical events. In the case of my adventures, the incident of the dog in the night time has seeped into the public consciousness as the definitive example of my skills. For those who haven't had the good fortune to hear about it before, the incident was a time when I precipitated my deductive chain on the absence of activity rather than the presence of such. A guard dog did not react when the horse was stolen, and thus we may safely deduce that the dog knew the thief. Nothing could be simpler once explained, and yet no other party realized until I told them. Inaction can be just as telling as action.

In Magic, inaction is the key to so much of my deductive work. Our opponent misses a land drop in her developmental turns, and we can safely conclude that she does not have one in her hand. Any reasonable opponent would play a land if they had one, so her inaction means she does not. Elementary. On the flip side of this coin, if our opponent appears by all metrics to have a fully functional hand and passes their turn without casting a spell during a pivotal stage of the game, we can rest assured that, in this case, their inaction means they have an instant speed effect they will be using their mana on during our turn. If somehow they do not have such an instant speed effect, our conclusion shifts to the idea that their hand is less functional than previously believed. Pay close attention to what your opponent does, but pay closer attention to what they do not do.

From Chapter Three: No New Criminal

Just as I was greatly benefited in my detective work by my extensive study of the annals of crime, so too does it behoove the dedicated Magic player to make a serious study of the history of the game. Every new deck has a close analog in the history of the game, and knowing how things played out before can help predict how they will play out now. The history of Magic is the story of Aggro and Combo and Control battling in a thousand different ways under a thousand different circumstances to a thousand different conclusions. There is nothing truly new in Magic.

Further, there is nothing new within specific metagames. The game is too big to have a niche interaction not championed by some aspiring Magician. The cream rises to the top, and those interactions and decks which are actually viable are there to be seen by the trained eye. The wealth of resources available to the student of the game in this age is remarkable. A true observer will never find themselves surprised by the cards their opponent chooses to bring to battle, having seen those decisions, no matter how rare, before in their extensive study. Indeed, they will use the rarity of those decisions against the opponent, pinpointing with great certainty what kind of player their opponent is, what internet resources they frequent and how they think. All from an innocuous combination of infrequently made decisions.

From Chapter Five: The Law of Mounting Evidence

What I have frivolously named the law of mounting evidence has been the hardest lesson for me to learn throughout both my detective career and my newfound Magic playing. As I told Watson in the beginning of our acquaintance, "I ought to know by this time that, when a fact appears to be opposed to a long train of deductions, it invariably proves to be capable of bearing some other interpretation." An amateur psychologist who I have recently made the acquaintance of tells me that my hamartia in this regard is shared by all of humankind. He claims that the human brain is designed to weigh newer information more heavily than older information. For detective work and for Magic, this is a tendency we must break in ourselves.

When one arrives at a read on a card in the opponent's hand through the good practices detailed in this work it is necessary for there to be a mountain of evidence. One single piece of evidence is rarely enough to make a definitive claim on what the opponent is holding. The counterpoint to this is that once a read is established, one piece of contradicting evidence does not invalidate it. The early clues we gathered about our opponent's hand do not become less important as the game goes on. Indeed, the argument that they are more important than later clues is one with considerable merit, as information from the early game is often more strategical and less tactical, offering insight into the opponent's overarching plan -- which was derived from their starting cards.

From Chapter Eight: Addition by Subtraction

The range of information that Magic players will hold in their mind with the thought that it is significant astounds me. Why the fact that you have only won two of your seven die rolls should interest me or you is beyond my ken, but I am at this point wholly convinced that I shall be greeted by a similar refrain from my opponent more often than not. It is probably no surprise to the reader that I am against such useless trivialities, now that Watson has made famous my declaration that knowledge of the Solar System is useless to me and my work. Well, let me declare here and now that a detailed, spreadsheet like knowledge of the statistics behind your performance in dice rolls on the day is wholly useless to your work as a Magic player.

Magic is mental warfare. You use every ounce of your available mental energy to outsmart or Outwit your opponent at every turn. Holding useless facts about die rolls in your head reduces the mental energy you have for the gameplay. Let it go. Similarly, pay attention to which of your observations are useful and might lead to valuable deductions and which are useless signal noise. When your opponent plays which cards is always useful information, while their emotional state as they play those cards may or may not be helpful. The times they choose to pause for thought are probably significant, as are the times they responded instantly, but response times in the middle are generally much less useful. Endeavor to forget every observation that will not aid your investigation -- there are better uses for your mental energy.