Altogether, there are three different type of cards:
Creatures are the fighters of the game. Each creature possesses various values, which impact the battle and can be played in either an active or supportive manner. There are also the heroes. These are particularly powerful creatures, which each player may only have once in their deck.
Spells are events initiated by the player to influence the course of the game. They must be payed with mana and can only be used once the player has reached the respective level.
Exactly like spells, these cards can only be played once the respective level has been acquired. Those cards are stored outside the deck and thus can be accessed at any time by the player. As long as those cards are active, they will be consistently beneficial. Only a hostile attack may destroy them
Learn more about the races of Rugon here.