Mana cost determines how many Mana points are deducted from a battle's Mana Cap when a certain card is drafted into a team.
Before every battle, the players are presented with a mana cap, the maximum number of mana points that may be used in the creation of their teams.
Every card (Units and Summoners) has a mana value, which can be found in the top left corner of the card as pictured below.
During team selection, a mana calculator will be displayed on the ‘Drafting a Team’ screen to indicate the mana usage. Teams can only be successfully submitted for battle if the total mana values of all the cards selected for the upcoming battle are equal to or less than the mana cap indicated.