You are allowed a maximum of 30 cards in a deck and each are played individually by dragging them onto the game board at the cost of mana. The default starter deck is the Council faction but as you play through the game you will be able to unlock other factions and earn new cards which can be used to customise your decks to suit your strategies.
The way cards are played is determined on what they are, the hero cards can only be played on eligible board tiles, weapon cards must be placed onto a compatible hero, and spell cards must be played on an eligible tile, hero, or crystal. Each of the factions will also have two specific powers that will provide an advantage when used, these powers consume mana and can only be used once per turn but are eligible for re-use on every turn.
Mana, Damage, and Health are displayed on each of the Hero cards. Mana (circle) is how much it will cost to play the card, Damage (star) is the amount of damage the hero will inflict on the target it attacks, and Health (heart) is the amount of damage the hero can recieve before being defeated. Some cards will also have Armour (shield) which protects a hero's health by depleting first and regenerating at the beginning of the round.