Haste

Haste is a status effect that allows the affected unit to perform two actions in a turn, provided it has the ability to act. For the purpose of additional action cost, doing this only counts as one action. A Hasted unit may also choose to perform only one action, and in this case, that action does not count as an action. Haste lasts a number of rounds equal to its intensity.

A unit cannot be Hasted and Slowed at the same time. If a Hasted unit would come under a Slow effect of intensity X (calculated after the effects of dodging and Slow resistance), the remaining duration of Haste on that unit is reduced by X, but it is not Slowed at all. If X exceeds the remaining duration of Haste on that unit, then Haste ends and the unit is Slowed, but the intensity of the Slow is reduced by what the remaining duration of Haste was at the time Slow was applied.

For example, a unit with 5 rounds left of Haste would receive Slow 3, the Slow is not applied, but there are now only 2 rounds left of Haste. In another example, if a unit has 2 rounds left of Haste and would receive Slow 6, it loses Haste and becomes Slowed, but the intensity of that Slow is decreased to 4.

What it Represents
Haste usually spells of the same name that grant faster actions in video games, especially RPGs. Otherwise, it can be any effect which increases celerity and speed.