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Deck Thinning: It's all about probabilities

by Patrick Allen

Deck thinning is a popular strategy in many tournament decks.  I'm sure you've noticed how many decks run multiples of the Onslaught fetch lands, for example.  But I think that lots of players don't even realize the real benefits of it.  In fact, I recently had a friend ask me, "why is deck thinning such a popular strategy?"

Well let's look at the basics first.  There are the obvious reasons that most deck thinning cards such as the Onslaught fetch lands, Demonic Tutor, Diabolic Tutor, and even Merchant Scroll allow you to search for cards that you may need to win the game.  A nice ability indeed!  But what if you already have enough of the card you would normally have searched for?  Such deck thinning cards are now wasted draws aren't they?  Wrong!  They can still search for support cards or let you hold reserve copies in case spells get countered or destroyed.  Seems obvious enough I suppose.  But there is another less obvious use for utilizing deck thinning cards.

One reason that the Onslaught fetch lands have become so popular is that they allow you to search for, and place a basic land into play.  This effectively thins your deck down by one card (the land played via the fetch land).  This is an extremely useful ability.  First off, it clears lands from your deck quickly so that later in the game you will be drawing more spells instead of lands that you already have enough of in play anyway.  But this is not the only useful ability.  Besides increasing the chance that you will draw spells in general, it also increases the chance that you will draw those key cards at critical moments.  For example, in a sixty card deck, you have a one in fifteen chance of drawing a card for which there are four copies in your deck.  Now lets say you have removed four cards in the deck somehow.  Now let's check again...  58 cards...  You now have a one in fourteen-and-a-half chance of drawing a four of card in your deck.  Now, let's calculate with full opening hands included (assume that the hypothetical card we are trying to draw is not in your opening hand).  You draw seven cards, turn one is a fetch land fetching a land.  Turn two you draw a card and it's another fetch land.  You play it and do the same as last turn.  That means that you now have 50 cards in your deck.  This gives you a one in twelve-and-a-half chance of drawing a four of card by turn three.  If you had not thinned your deck at all, you would only have a one in thirteen chance by turn three to draw the same card. I think you see where this is going.

And it adds up!  If you keep thinning your deck by more and more cards, your chance of drawing certain cards will only get better and better.  Thawing Glaciers is a great card for this.  Not only can it make sure you have lands when you need them, but it will continually thin your deck more and more, turn after turn and continually increase your chance of drawing the critical cards in your deck.

I often hear of the controversy surrounding the exclusion of Land Tax from Legacy tournaments, but I often wonder why such controversy exists.  It makes perfect sense to me that it not be allowed.  Not only does it allow your deck to run insanely low amounts of land and still be playable, but it allows the deck to thin three cards from itself when it activates.  The increased chance to draw critical cards will mount quickly with this card in the deck.  Whoops, there's that crazy deck thinning thing again!  It's not quite as good as actual card drawing, but not every color has access to efficient card drawing, and sometimes you don't want to splash another color just for the ability to draw a few cards.  Deck thinning is a good alternative since it will still help you gain access to the cards you need to win the game.  And with a lot of restricted cards in Vintage, this is even more useful to help make sure you get those restricted numbers.  Not to mention that deck thinning in combination with card drawing is even more effective!

One of my favorite tricks is to use a full compliment of Urza's Baubles and Mishra's Baubles in my deck.  Forget the affinity madness these cards have (and believe me4, it's insane), but this trick can be used in any deck at all.  When Magic tournament rules were changed to require all players to run at least 60 cards, it was done so because the smaller decks were winning too fast, too efficiently because they were drawing the cards they needed to win way too quickly.  Using four Urza's Baubles and four [Mishra's Bauble[/card]s effectively allow your deck to be 52 cards.  Sure you still have 60 actual cards, but you can effectively write out the Baubles since they cast for free and thin your deck by one card.  Let's go back to our earlier example and recalculate drawing percentages.  At 52 cards, minus seven for the opening hand, that leaves you with 45 cards in the deck.  Assuming again, that you did not get a copy of the card in your hand and all four are somewhere within, this gives you now, a one out of eleven-and-a-quarter chance of drawing a four of.  Looking much better than a one out of thirteen-and-a-quater chance to draw that same card if you don't have any deck thinning now, isn't it?

Deck thinning is all about increasing your probability of drawing key cards that will allow you to win the game.  Even just splashing a bit of it into your deck can help your deck to run more like a well-oiled machine.

Last edited 12/8/2008 3:12:43 PM Page 1 of 1  Prev  Next  Go to page:

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