Mana curve

The "mana curve" is the distribution of costs of one's spells when building a deck. Calling it a curve is a misnomer as each mana value is discreet, but the term has persisted in the lexicon. By organizing the cards that are to go into a deck by their casting cost, a player can see how likely they will be able to optimally utilize each turn's mana (i.e., to play a card or cards with a casting cost or costs with a total equal to the mana available on that turn). A player who misses a spot on the "curve", generally defined as failing to use mana, is said to be behind on tempo. In order for a deck to curve out properly it must also maintain color balance.

Description

Mana curves are generally built on the premise that power scaling is at least mostly linear: a three-mana spell is more powerful than a two-mana spell, and a four-mana spell is close to twice as powerful. This may lead players to believe that they should have a curve weighted to the higher end. While this holds to some extent in Limited Magic, Constructed leans towards the power outliers and so decks are built around cards rather than curves. A card such as Lovestruck Beast is a three-mana card that can invalidate certain five-mana cards, making it so that any cards more expensive than three that don't match up to a 5/5 invalid options. Removal is of a similar vein: if three-mana removal is the best option, a player using all two-mana creatures will likely win out. Conversely, if two-mana removal is prolific, all creatures more expensive are less viable. The discreet nature of mana and spells also informs this: a curve that peaks at three mana will not be able to increase tempo by casting two spells until six mana is achieved, while a curve peaking at two will be able to at four mana. Hence, the argument against a higher-weighted curve is that each addition of mana requires another mana source, and due to the probabilities of distribution, missing out on either piece is a fast way to lose.

Related to this, there is a minimum level of functionality that one-mana cards can have, so at a certain density a deck full of one-mana cards becomes powerful, as the logic between four and two is magnified when comparing two and one. Mono-Red and Sligh was historically the pioneer of low curve decks and mana optimization theory and remain a fundamental check on gameplay today.