From Shadow Era Wiki

Haste is an ability in Shadow Era.

Haste allows for an ally with the ability to attack and use any abilities on the turn it is summoned, whereas normally allies are exhausted upon being summoned. Some allies have haste as one of their own abilities, other times they can be given haste by card effects. It is important to note that haste does not apply to allies that are "returned to play", only to summoned allies, so allies revived by Gravebone's ability won't be able to gain haste for example. This ability was introduced in Call of the Crystals.