Cube Mana by the Numbers: Colored Sources, Splashes, and Fixing

At Level 1 you learned the habit: 17 lands, split by your colored symbols. That works for most two-color decks. This lesson shows the numbers behind it, so you can build a mana base on purpose: when to shade toward one color, when a splash is worth it, and how much a dual land helps.

Every figure here is worked out from a 40-card deck with the standard hypergeometric formula, the math for drawing cards without replacement. They leave mulligans aside, which helps a little in real games.

Sources, not lands

A source is any card that can make mana of a color: a basic land, a dual land, a mana artifact, a creature that taps for mana. A Forest is one green source. A land that taps for green or blue is one green source and one blue source.

So the question is not “how many Forests?” It is “how many green sources?” A deck with 17 lands and three dual lands has more than 17 sources in total.

How many sources a color needs

Here are the chances of drawing at least the sources you need, on the play, in a 40-card deck. On the draw you see one more card, so the odds are a little better.

The color name is only an example; the numbers work for any color.

What it tells you:

• A main color with cheap spells wants eight or more sources. Below seven, your two-drops get stuck.
• A color with double symbols, such as a card costing two of the same symbol at four mana, wants nine or ten. Two sources by turn four is much harder than one.
• In an even two-color deck, 17 lands split nine and eight works for both. Dual lands push both counts higher at once, which is why they are worth picks.

The real odds of a splash

A splash is one or two cards from a third color. The table shows why it needs care.

With three sources, you have about a 63% chance of at least one by turn five. With four, about 74%. With five, about 82%.

So a splash on three basic lands means your splash card is stuck in hand roughly one game in three, even by turn five. And every basic you add for the splash is one fewer source for your main colors.

A splash pays off when:

• The card is much better than what it replaces, usually a bomb or premium removal.
• It costs a single symbol of the splash color and is not needed early.
• You have dual lands or artifacts that add the splash color without cutting a main-color source. Four or five splash sources, mostly from fixing, is a sound splash. Three basics alone is a gamble.

Land count, revisited

The same math explains 17 lands. Chances of at least three lands in your first nine cards, which is turn three on the play:

Each land below 17 costs about five points of hitting your third land drop on time. That is a fair price for an aggro deck with a curve that stops at three. It is a bad price for a deck with five-drops. Our guide to Cube land count covers the same tradeoff from the owner’s side.

Mana artifacts and creatures that make mana count toward your sources, but they are fragile. Many players count two of them as about one land when deciding how many lands to cut.

Shading toward your cheap spells

If your two-drops are mostly green and your five-drops are mostly black, give green the extra source even if black has more symbols in total. Early mana matters most, because a missed early play costs a whole turn. Late spells can wait a turn for their color.

A building checklist

1. Count your colored symbols, and note which color your cheap spells need.
2. Count your fixing: dual lands, mana artifacts, mana creatures.
3. Give your main early color at least eight sources.
4. Splash only with four or more sources, ideally mostly from fixing.
5. Play 17 lands unless your curve stops at three.

Our piece on the Cube mana curve shows how curve and land count work together.