Tuesday, April 17, 2012

2nd Command (EDH) and Probability for Deck Construction: Applications of the fractions 1/3 and 1/4.


Hopefully, you don’t try to rig your deck through cheating.  This is for the people that are interested in making their MTG a game of chance.  It’s only natural to want to select certain cards, and often cards can be grouped, such that in a 100 card Commander deck, or any deck for that matter, there are certain formulas that can be used to determine things such as how many lands one is likely to get in their opening hand, or how many elves one is likely to have by turn three.
1/3
Let’s start with the basics.  The first blog was on the fraction ½.  Now, we will start with the fraction1/3.  In a Commander deck, there are 100 cards and a Commander.  Consider that 99 cards might as well be 100 cards.
Where might this fraction, 1/3, be useful?  1/3 is useful for lands, and certain scenarios.   That is, if you have 33 lands out of 99 cards, that fraction is equal to roughly 1/3.  Also, you might want to construct your deck with 1/3 elves, for example.  Keep in mind this is probability so the fractions need not be exact, and one should round numbers where it is appropriate.  For, example, just because one can use a rounding technique doesn’t mean that it should be used.
Consider this, if one in every three cards is a land, then you have a 33% chance of drawing a land.  This is important because it is almost always necessary to have 2 lands in an opening hand.  In an opening hand one has 7 cards, and then possibly 8 cards if he or she draws on the first turn.
First, consider 7 or 8 cards.  If 1 out of every 3 cards, or roughly 33% of your deck is land, you can multiply 7 or 8 by 1/3.  33/99*7=2.33  Thus, in an opening hand, one is likely to have either 2 or 3 land cards.  In the case that 8 cards are drawn, 33/99*8=2.66.  Thus, in that situation it is likely that you will have 2 or 3 lands, but through rounding, it is actually more likely to have 3 than 2.  This is the amount of land you can expect to have in your opening hand.
Consider on turn 1 you have ~2 lands, as has already calculated.  That means that on turn 3 you have ~3 lands because 33/99*9=3.  That is, in a normal scenario, it is likely that you will likely have 9 cards by turn three, and 3 of those cards will likely be lands.
Though you want to have at least 2 lands in your opening hand, sometimes it is more important to consider when you will run out of lands to play.
Consider the following situation where there is no mana acceleration, and 33 lands in a commander deck.  It would also be the same if you put 33/99 cards of any kind.
Turn 1, 7 cards, 2.33 lands, play 1 land, 1 lands left
Turn 2, 8 cards, 2.66 lands, play 2nd land, 0 lands left
Turn 3, 9 cards, 3 lands, play 3rd land, 0 lands left
Turn 4, 10 cards, 3.33 lands, no land to play, 0 lands left
Turn 5, 11 cards, 2.66 lands, play 4th land, 0 lands left
In a 60 card deck, 1/3 of the deck would be 20, as 1/3*60=20.  Thus, if you are playing a variant like standard or extended, then in order for roughly 1 out of every 3 cards you probably want to consider putting 20 land cards in a 60 card deck.
¼
Now there are two references points 1/2 and 1/3.  That is, it should be possible for one to figure out how to make a deck based on ¼.  If 50/100=50% or one of every two cards, and 1/3=33.3%, or one out of every 3 cards, can you guess what fraction one might use such that 1 in every 4 cards is a certain type of card?  I’ll give you a hint: 4 quarters make $1.  Thus, it is such that if you want for ¼ of your cards or one out of every 4 cards to be an elf, a mid game card or a heavy hitter, for example you will want to make 25% of your deck to have say a mid game card.  25% of 100 cards is equal to 25 cards, which is analogous to the idea that 4 quarters make a dollar.
Consider the following and that you won’t be able to play a mid game card right away:
Turn 1, 8 cards, play 0 mid game cards, 2 mid game cards left
Turn 2, 9 cards, play 0 mid game cards, 2 mid game cards left
Turn 3, 10 cards, play 0 mid game cards, 2 mid game cards left
Turn 4, 11 cards, play 1 mid game card, 2 mid game cards left, total Planeswalker mid game cards = 3
Turn 5, 12 cards, play 2 mid game cards, 0 mid game card left, total Planeswalker mid game cards = 3
In the case of a 60 card deck making 25% of the deck to be mid game cards is 60*.25=15 cards.  Thus, if you want for a chance of ¼ of drawing a certain type of card in an extended or standard match, then including 15 cards of that kind is a good idea. 

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