When you are building a constructed deck for Hex, you are limited to having a maximum number of 4 of each card in your deck. This rule is born of the same rule in Magic the Gathering, where it came about because back in Alpha Magic, the Plague Rat deck was crazy good (Plague Rats had Power and Toughness equal to the number of Plague Rats in play) and you could make your decks hyper consistent if your play group had access to a large pool of cards (45 cards was the deck minimum in the Alpha rulebook).
That said you know you want 4 of your key cards in your deck, for consistency’s sake. But with 3 sets under our belts, there’s a ton of good cards that make your deck better and it’s impossible to include all of them at a rate of 4x each in a 60-card deck. So when do you lower your counts on cards?
Opening Hand Odds
Using a hypergeometric calculator, we can determine the chance of seeing 1 or more of a card in your opening hand of 7 cards.
If you have four of a given card in your deck: 39.9499% chance of having 1 or more in your opening hand. 6.321% chance of having 2 or more.
If you have three of a card in your deck: 31.54295% chance of having 1 or more in your opening hand. 3.354% chance of having 2 or more.
If you have two of a card in your deck: 22.14689% chance of having 1 or more in your opening hand. 1.186% chance of having both.
If you have a singleton in your deck: 11.67% chance of having it in your opening hand of 7 cards.
Unique cards are one area you can look at lowering your count. Maybe unless you are playing Exiled Bard (which gains power for each unique played), you never want a hand with multiple uniques, unless that card is the backbone of your deck AND you need it early (I’m looking at you Reese the Crustcrawler). Low-drop uniques can usually be played three-of without much problem (almost halving the chance to end up with two or more in your opening hand), but expensive uniques may want to go down to just a pair in your deck, depending on how often you expect them to make a difference.
Cards that cost 6 or more are not what you want multiples of in your opening hand (unless you have a crazy ramp deck, then go for it). The difference between 4 and 3 is around 8.5% and the difference between 3 and 2 is 9.3%. You need to do some investigating on what turn you want a high-cost card AND how often that card will actually be useful.
On turn 8 if you have four of a card in your deck: 69.445% chance of having one or more in your hand.
On turn 8 if you have three of a card in your deck: 58.533% chance of having one or more in your hand.
On turn 8 if you have two of a card in your deck: 44.0677% chance of having one or more in your hand.
On turn 8 if you have a singleton in your deck: 25% chance of having it in your hand.
As you can see, two or three of a card is dramatically different than running a single copy. Most of the time you want to be running 2 or 3 of a high-cost card; the higher the cost the fewer you want.
You almost always want 4-of any low-cost (3 or less), non-unique troops. The tempo you can gain and maintain with a board of low-drops might be worth the lack of power while you fish out your larger troops and win conditions. In addition, late game chump blockers might make all the difference between you and certain doom. Only situational low-drops are where you might consider lowering your count to three or less—and if you want less than three of an inexpensive card in your deck, you may want to re-evaluate whether you need that card in your deck at all.
“Situational” refers to cards that might be dead cards in your hand if your opponent’s board hasn’t developed like you thought it would (like Turbulence for instance). Here you need to weigh against the threat they are meant to deal with. This is especially true with reserves, and whether you want to bring in four of something or if you can get away with three (or even two, if it’s meant to be a save vs. a late-game situation).
Non-unique game winners/game changers
These are the 5-or-less–cost cards that can save your bacon (Extinction) or put you in a position to win (Countermagic/Vampire King/Angel of Dawn/etc.) If you ever find yourself considering dropping these from 4-of to anything less, ask yourself if its worth the risk. Look at the percentages I gave above for Opening Hand and Turn 8. Are those percentages you can live with? Is the card you are cutting for REALLY going to make up the difference?
So there you have it. The above logic works not just for constructing your deck, but also for what, and how many, to bring in from the Reserves. Of course nothing trumps the hypergeometric calculator like actual playing with the deck. Seeing what the draws are and what your lines of play turn out to be can trump anything you might determine statistically, so get out there and play some constructed Hex! See you in the queues!