How to Make a Good Cube
I have been playing Magic the Gathering for a sufficiently long time that I have ,at some stage, been almost every kind of player that there is: The terrible child, the cocky annoying teen, the enthusiastic grinder, the pro, the mentor, and now I fear I may be heading towards being the forgetful old man! My first encounter with a magic cube was around 2004. It was badly designed, almost half the cards were blue. It looked horrible, loads of the cards were proxied on the backs of other cards in black marker. It made for a confusing set of games yet it was still the most fun I had ever had in Magic. Without much delay, I had set about making my own cube which I have loved and maintained to this day. It has travelled to many places and been played by many Magicians. While I no longer play competitive magic, I have remained a regular and keen cuber. I maintain that it is the most diverse and skill intensive format as well as, most importantly, the format that is the most fun.
For those who have not yet encountered a cube I shall briefly describe what one is. A cube is essentially a collection of cards that you usually draft in some way, build a deck and do battle against the other drafters. Most other things are very much down to the discretion of the cube's owner despite the original premise was to include one of each of the most powerful cards in magic. The size of a cube is usually between 360 and 720 cards. Less than 360 and you cannot really do an 8 man draft while more than 720 is rarely called for and makes things unwieldy and potentially dilute the experience.
One of the aspects of cube I enjoy a lot is the process of keeping up with recent sets, adding in new cards and then adjusting the rest of the cube accordingly to suit the new additions. I keep a reservoir of old cube cards and potential cube cards so that I can cycle the borderline cards in and out alongside the cards from the latest sets. This keeps the cube format fresh and allow it to evolve smoothly over time.
The stereotype of which cubes are expensive to put together only applies if you’re copying those people who have most powerful cards. I have seen good pauper cube lists that only have common cards and those cubes can be put together for a fraction of the cost of a typical cube. You don't even have to go the pauper route to enjoy cube on a budget either; you can simply create one from the best cards in your collection and add to it over time as you get more stuff that you want for it. It won't be as powerful as many other cubes but this is not a bad thing. The important parts of the experience are not affected. What makes a cube better compared to other drafting formats is that every card you might be able to play in a pack is powerful, there are very few dud picks. This makes for a lot more choices, you get to really sculpt your deck as you draft rather than taking the only playable card from each pack.
A common distinction between the more standard cubes like mine is if they are powered or not. This refers to cards like Ancestral Recall, Black Lotus, Time Walk and the Moxes and if you have them in your cube. There are arguments for and against their inclusion and I have tried both. The powered cards are a lot of fun and they let you do some amazing things. The problem with them is that they lead to much more random games. The person with the most power, who draws the most power is far more likely to win. It also takes a little out of the draft as you pretty much always first-pick power if you have the option. Less choices and more luck equals a more lackluster format.
I now run an un-powered cube, I was killed one too many times by a turn one Black Lotus into Elspeth, Knight-Errant plays and decided to calm things down. There are a few cards classically not included within the descriptive term “Power” that I have also cut from my cube. Those cards were all of comparable power level to the actual power cards and by removing them the format became much fairer and more skill intensive. The list of “banned” cards for my un-powered cube are:
Mox Pearl, Jet, Sapphire, Emerald and Ruby
Library of Alexandria
I don't have a Timetwister in my cube either at present, not because it was too powerful and needed banning but because without the other power cards it was hard to exploit and as such barely ever saw any play. The worst thing about removing these power cards from the cube is that it hits combo archetypes really hard. A powered cube is balanced by the trilogy of aggro, control and combo. The un-powered cube is balanced by the aggro, mid-range and control trio. It is much harder to build cubes that will allow you to do a selection of good combo decks as it is and so I am content to play less combo in return for better games all round. If you are really all about combo decks I would recommend doing a combo only cube before making one that allows for other archetypes as well as the combo ones. They are much easier to design and will give better decks and games as a result. In combo centric cubes it matters much less if you use power or not as well.
Assuming you are looking to build a more typical cube like mine, one with one of each of the most powerful cards, then how should you design it so as to get the most out of it? A lot of people get hung up on strictly adhering to the premise of most powerful cards and overlook the interaction between cards. There are many humble cards that I have in my cube that are far better in that environment than yet another powerful top end monster. The aim of cube is to have the most fun, as such you should take “the most powerful” as a guide rather than a rule. Once you have a framework of the obvious most powerful cards in magic you want to then supplement those cards with things that will give the best decks and games and not what you see as the next few sets of most powerful cards.
You want the mana curve of your cube to somewhat reflect the mana curve of the decks that you will be building from it. Most of the decent cube deck have either a fairly flat mana curve with similar numbers of one through five or six drop cards, or a downward mana curve with ever decreasing numbers of cards in each slot as you go up the curve. You simply can't build good decks that have no one drops, a couple of two drops and so forth until you have a pile a bomb six drops. As such you want your cube to have lots of one, two and three drop cards and then a decreasing number of higher cost ones. If you just include the most powerful cards then your cube will end up curving in the wrong direction and all the best cards will be the cheap rare ones and not the classically regarded powerful things like Jace, the Mind Sculptor.
It is wise also to keep the number of each coloured card roughly similar to each other. You can vary the number of artifact and land cards as much as you like, as this has little effect on the draft within reason. If, however, you have twice as many blue cards as any other colour, this will drastically distort the way in which you end up drafting. It can be done, and indeed will be very much the case if you do a combo only cube, however I recommend against this until you have some experience with cube design and sticking to an even colour distribution. It doesn't matter much at all if there are a couple more of one colour than another, if I add a red card I don't then go and find something else to add for each other colour but I do try and keep things a bit more even. The bigger your cube is, the more of a colour imbalance you can have without much detriment.
Gold cards are a bit trickier. As with artifacts and lands, it doesn't matter that much on the total number you have relative to other colours. You can have few gold cards or absolutely loads, the latter will incentivise more three colour decks and should therefore command a higher land count. What you have to be a little bit careful about is balancing the mana symbols a bit within the gold pool. You will find that green has quite a lot more potent gold cards than other colours; with blue and white having slightly fewer. It is not quite as important as with the mono coloured cards but it is still good to get a relatively even distribution of mana symbols. If you attempt go for a relatively even split of the various two and three colour combinations of gold cards you will certainly have to include some subpar ones or cut some very potent ones and that isn't worth the pay off. Gold card are inherently less playable than mono or colourless cards and so if you have too many gold cards it can lead to boosters having no picks for people a bit sooner than you might like.
I love lands, I don't even love gold cards that much but I have an awful lot of land in my cube. I like Magic which it is not decided by mana screws, I also like to be able to draft optimal decks wherever possible. As such, I have found that I play almost every cycle of half decent dual lands as well as a bunch of the better utility and man lands. Even the weaker lands remain much more commonly played than your average non-land card. All decks need land, typically around a third and so I have no real issue adding lands to the cube to reach that proportion. This, as with having too many gold cards, can lead to having lower number of useful picks in packs and packs running dry sooner than you might like. Still far less quickly than in normal booster drafts but still, something to be mindful of. I typically find I draft a little more than 45 cards which helps offset the high land count I like to run. This is certainly a wise thing to do when you are playing with less than 8 players. In a six man draft we will typically do 5 or even 7 packs, with 11 cards each.
Archetypes are a big thing in cube much like in other magic draft formats. Even if you don't really intend to do it, they will appear over time. Once you know which are the most powerful and/or easiest decks to draft are and what the good things are against such decks; you will start to look at cards not in terms of there raw power so much but how they will fit into the various decks that are most commonly built. Not many cards are sufficiently powerful to shift a whole cube metagame to allow for a whole new archetype. That means most of your new additions will be cards that need to have had some sort of a pre-existing home.
You can force archetypes to exist in your cube if you wish. If you really enjoy certain decks you can put all the key cards in and it will usually allow you to draft and build that deck. Examples of this include tribal decks such as Goblins and Elves, Affinity, Reanimator, Splinter Twin and so forth. I used to cater for all of what I regarded as the most powerful possible archetypes in cube. This was quite fun but it hurt the draft portion somewhat, as there was typically little overlap in your card pools leading to a fairly non interactive draft.
I have found that the best overall draft and game experience occurs when you have as many cards in your cube as possible that have broad application and can be played in a wide array of decks. Some affinity cards are indeed very powerful, such Cranial Plating or Arcbound Ravager and so forth, but are pretty unplayable in any other deck. Cube already has far more power and synergy than any other format, you can sacrifice a little of both and have a much more interactive draft with lots more choices as well.
Another way to look at this is that you are trying to create a format with as many possible different archetypes as you can without overly diluting your card pool. It can include a perfect 40 card Affinity deck in your cube, but if you are running 720 cards and only using half of them in a draft the odds are that there will not be a viable affinity deck possible from the card pool. You want some redundancy in core effects such as ramp in green, burn in red etc. so that even when not using all the cards you still can reliably assume you will still be seeing those things. If you have a 720 card cube you will need twice as many cards for each archetype that you support.