There is a concept in military and business circles of the Tooth to Tail Ratio. Rather than being a metric for ancient crocodiles, this is the ratio between the active combat forces (“Tooth”) and support services (“Tail”) in your military. On the business side, it can be used as a distinction between R&D plus sales and all the other staff – IT, maintenance, and so forth.

The casual observer tends to think that the military is mostly “tooth.” Sure, there are those dudes on the aircraft carrier who wave at Tom Cruise while Kenny Loggins plays in the background, but it’s really all about the F-14s, right?

We often think about mana bases in Magic in the same light. Sure, they’re a necessary part of the deck, but we’re inclined to just write “and 25 lands” and then move on to the cool stuff, the “tooth” of our deck – the spells.

Except that those F-14s required some fifty hours of maintenance per hour of flight time. Your mana base may not require quite that much attention, but if you turn your brain off and just pile some lands in there, it’ll be very much like being Tom Cruise without all those dudes on the carrier deck.

It won’t end well.

Today I’m going to plunge into the world of mana bases with a particular interest in the idea of color depth versus color coverage -- that is, not just which colors your mana base supports, but how well it supports them. I’ll start by explaining a bit about both ideas, then move on to discussing how they impact deck design and deck tweaking, and how they explain why modern RUG decks can be hard to play correctly.

Color coverage versus color depth

I came to this week’s topic as I was trying out a Standard W/B/G (aka “Junk”) build. I liked the deck, but I noticed that it had a curious tendency to falter on its mana despite having reasonably robust color access. With a mana base of 25 lands, my color access looked like this:

In support of a black splash for removal spells in an otherwise W/G deck, this seemed reasonable. Compare that color distribution, for example, with an example W/U/B Caw-Blade deck:

Clearly, their color coverage is somewhat better, but is that the only difference?

Well, no. The real issue here is not the difference in color coverage, but the difference in color depth. Let’s take each of these concepts in turn.

Color coverage

Color coverage is a pretty straightforward idea. How many lands do I have that can provide each color I want to use? Clearly if we’re under some cutoff, we either need to alter the mana base to suit our needs or play ramp spells or mana producers to give us access to the colors we need.

For example, here’s the color coverage for Josh Silvestri’s recent U/W Caw-Blade list:

…and here’s the color coverage for A.J. Sacher’s red-splashing Caw-Blade list:

Just operating from this point of comparison, it looks like the U/W/R deck has managed to slide in access to the color red at little to no expense in terms of access to white and blue. In fact, it even has one more white source than the U/W list.

But that’s color coverage, and as I’ve emphasized above, it’s not enough.

Color depth

Where color coverage talks about how many of our colors we have access to, color depth refers to how much access we have to those colors simultaneously.

Consider the very basic example of the following pair of highly theoretical mana bases:

Simple R/G

[draft]4 Wooded Foothills
4 Evolving Wilds
8 Mountain
8 Forest[/draft]

Dual R/G

[draft]4 Copperline Gorge
4 Raging Ravine
8 Mountain
8 Forest[/draft]

These mana bases have the same color coverage profile:

But you can probably tell, at a glance, that they’d play out very differently – and this is what was ambushing me in that Junk mana base earlier. The difference between these two mana bases is in the color density in those “dual” lands.

Whenever I play and use a [card]Wooded Foothills[/card] or an [card]Evolving Wilds[/card], I have to choose to select either a Forest or a Mountain. Although these lands give me access to both colors, they have an effective “color density” of one – at the end of the day, they give me one color.

In contrast, when I play and use a [card]Copperline Gorge[/card], I have access to both colors for that turn and every turn afterward. Gorge and Ravine have an effective “color density” of two – each turn, they give me access to both colors.

How color depth impacts our building and refining

The idea of color coverage versus color depth may not be especially profound on an intuitive level, but I’d bet that you’re not consistently tracking it during your actual deck building…or, perhaps more critically, when you modify an existing design.

Tools for mana base building

Over time, I’ve found myself doing more things with spreadsheets – including in Magic territory. Spreadsheets help automate certain aspects of deck design so that we can catch issues like accidentally modifying a mana base until it no longer works. This might come off as too much effort for the job, but it’s really a matter of a little up front investment to make things much easier on yourself as you go along.

My current mana base spreadsheet looks like this:

It’s still a pretty manual affair, but the essential point is that I can type in the lands I want to use along with a few associated numbers, and it reports back to me about color coverage and color depth.

“Number of lands in each color” reports on color coverage. In the example mana base, it lets me know that I have access to 18 white sources, 16 blue sources, and 12 red sources. If you’re having trouble finding that part, it’s the first line with colored entries, below the big list of lands.

“Density in color” reports on color depth. It tells you, effectively, how often you have access to that color in an overlapping manner with another color. Higher is better.

You can skip this part if you don’t care, but here’s what density actually reports on:

Density in color = ( sum of all ((# of Land N) x (color density for Land N)) for all land types) / (total land count)

In other words, if your mana base were entirely composed of dual lands, your density in each of the two colors would be “2.”

So a low density in a color means we often have to choose to have that color or have some other color. A high density in a color means we frequently get to have both that color and some other color at the same time.

I’m going to use these numbers in our discussion going forward, but if you don’t feel like monkeying with spreadsheets, don’t worry – the principles apply no matter what, and I’ll end with an easy “rule of thumb” test for the same thing.

Color depth in action

Earlier, I ran out the color coverage numbers for Silvestri’s U/W Caw-Blade and Sacher’s U/W/R Caw-Blade. As a reminder, here are those numbers one more time:

Now, take a look at their density in those colors:

What do these numbers tell us?

First, we can see that the U/W mana base tends, more often than not, to simultaneously give us access to both colors. This makes sense – it runs twelve dual lands. The U/W/R list gives us simultaneous access to white and blue slightly less often, but it’s still reasonable. Again, this makes sense – it runs eight duals lands, which is not as impressive as the pure U/W list, but is still pretty good.

However, the color density for red in the U/W/R list is an abysmal 0.4.

But we know that A.J. did well with this list. So what gives? Is this a useless stat?

The practical significance of color depth

That low color density stat for red in Sacher’s Caw-Blade list means that if he wanted access to red, he had to choose not to have access to white or blue. In contrast, the higher values for white and blue mean that he frequently didn’t have to choose between white and blue when he made a land drop, getting access to both.

This makes sense in light of the deck’s actual mana base:

U/W/R Caw-Blade mana base

[deck]3 Island
3 Mountain
4 Plains
4 Arid Mesa
3 Celestial Colonnade
2 Evolving Wilds
2 Glacial Fortress
3 Scalding Tarn
3 Seachrome Coast[/deck]

The access to red in this list comes from Mountains, Arid Mesas, Evolving Wilds, and Scalding Tarns. That’s one basic land and three types of fetch. Thus, your choices related to red access are:

Play a Mountain
Choose to fetch a Mountain instead of an Island ([card]Scalding Tarn[/card])
Choose to fetch a Mountain instead of a Plains ([card]Arid Mesa[/card])
Choose to fetch a Mountain instead of an Island or a Plains ([card]Evolving Wilds[/card])

…and this works pretty well for the list because the red cards it’s trying to cast are:

[draft]3 Lightning Bolt
4 Cunning Sparkmage
1 Inferno Titan[/draft]

Access to a single red is plenty if you’re Bolting and Sparkmaging all day. That Inferno Titan is a little suspect, except it’s a one-of and it comes in at six mana, meaning you can probably afford to choose a Mountain over and Island or Plains by the time you’re at your sixth land drop.

But what you really couldn’t do in this deck would be to run [card]Goblin Ruinblaster[/card]s. Sure, the color coverage is decent, but the lack of density in red means that either:

1) You’re never kicking them

…or…

2) You’re going to accidentally cut off access to some of your other cards

The first case is obvious – if you have one red, you can’t pay RR to kick Ruinblaster. However, the second case is the real point. A deck like this one frequently offers you the choice to pick access to red over access to blue or white. That’s the point of the color density stat – it tells us, roughly, whether or not we have to pick access to that color over access to any other color in our mana base.

Say you cavalierly stick some Ruinblasters in your U/W/R Caw-Blade deck, and on your third turn you crack an Evolving Wilds for a Mountain so you can Ruinblast your opponent’s Valakut. If that leaves you with these lands:

[draft]Celestial Colonnade
Plains
Mountain
Mountain[/draft]

…then you’ve cut yourself off from these cards:

[draft]4 Jace, the Mind Sculptor[/draft]

If you had an Island instead of that Plains, you’d be cut off from:

[draft]3 Gideon Jura
4 Day of Judgment
1 Sun Titan[/draft]

Neither one of these choices is very hot, and they provide a compelling argument for not running Ruinblasters (as, indeed, people don’t).

Color depth in deck design

The case for keeping track of color depth during deck design is pretty obvious. You want to make sure you’re building a deck that can actually cast its spells. A mana base like the U/W/R Caw-Blade list above can support double white and double blue simultaneously, but can’t carry the burden of a lot of double red – not without screwing up how the deck plays.

Here’s the color density for that Junk mana base I was talking about earlier:

…and suddenly, the problem is clear. Even though I wasn’t attempting to cast any spells with more than a single black in the cost, the mana base as I’d built it required too many choices between its constituent colors. I frequently had to choose black rather than one of the other colors, and all too often had to choose between green and white as well. The end result of all those choices was a deck that, in playtesting, often found itself locked out of a second green or a second white, cutting off access to a whole swath of spells.

So our general rule is that, absent other forms of mana fixing, we want to make sure we aren’t trying to cast spells with double or triple color in their casting cost if we have a low density in that color.

It’s an intuitively obvious rule on the face of it, but it’s all to easy to confuse color coverage for color depth and find ourselves playing a deck that can handle all sorts of mana costs…just not all at once.

Color depth in deck tweaking

Whereas mana bases earn a lot more of our attention when we’re designing a new deck, they’re way down on our radar when we’re tweaking one. Would you have tossed Ruinblasters into that Caw-Blade deck? Maybe. It can make a lotta red, and it already has an [card]Inferno Titan[/card], right?

In tweaking a deck, it’s easy to accidentally “creep” the design into a state where it no longer has enough color depth to support all the cards you’re stuffing into it. This is very much like how we sometimes screw up the curve in a deck as we attempt to rejigger it to fit the ongoing metagame.

The lesson here isn’t any different than the one about deck design, except that you still need to stay vigilant even if you’re just updating an existing deck. The temptation will always be there to toss in a few extra cards to shore up a matchup, and you may not realize that you’re actually disrupting the flow of the deck.

…or, alternately, it may inform your tweak. Is it critical that you cast those kicked Ruinblasters in your Caw-Go deck, and no other card will do? Then perhaps in sideboarding, you’ll take out either those Jaces or those Days and Gideons, since you know that you’re going to get stuck choosing between Ruinblasters and white cards, or Ruinblasters and blue cards – so why not get ahead of the game and just preemptively ditch one side of that problem?

Color depth in generating play complexity

As a final note, some very effective decks have curious color depth stats. Here’s the mana base for a recent RUG list:

RUG Control mana base

[deck]3 Forest
5 Island
2 Mountain
3 Copperline Gorge
2 Halimar Depths
4 Misty Rainforest
4 Raging Ravine
4 Scalding Tarn[/deck]

Here’s its color coverage:

Decent enough. Here’s its density in each color:

So, did playing RUG decks ever strike you as hard? These density numbers show some of the reason why. This deck requires choice after choice between color access options…and then wants to cast [card garruk wildspeaker]Garruk[/card] (GG), [card jace, the mind sculptor]Jace[/card] (UU), and activate [card]Raging Ravine[/card] (effective RR). As the pilot of the RUG deck, you need to properly sequence your plays such that you get to access the right color combination at the right time – make a mistake and you’ll find yourself cut off.

…and this version of the deck plays [card]Explore[/card]s, but no Oracles (it’s Bobby Oleksy’s list from the Memphis Open).

The color depth on this list kind of sucks. But the deck is otherwise tremendously powerful – so if you can stay on the ball and sequence your color access properly in each and every game, then you’re going to do well.

In other words, being “color shallow” is not automatically bad…but it does present more opportunities for operator error.

A caveat and a rule to conclude

In closing out this discussion of color depth, there are a few things to mention.

First, I made a throw-away remark up there about “absent other forms of mana fixing.” This is a big deal, of course – if you have reliable ways other than your mana base to get color access, or you can just have “more mana base per turn” than normal via acceleration, you can get away with skimping in terms of color depth…at least to an extent.

Second, if you don’t care for spreadsheets, then you can just keep in mind that “more duals is better” in colors in which you want to play double or even triple-color spells. As a corollary, you should be suspicious about the stability of your mana base if you find you’re leaning mostly on fetchlands to get all your colors.

Finally, if you do like spreadsheets, you can get the one I’ve described today by clicking here.

Hopefully, either the spreadsheet or “rule of thumb” approach will let you tweak your decks to your heart’s content without accidentally locking yourself out of a critical color.

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