Currently, we have 3 types of cards: Units, Spells, and Enchants:
Units are permanent, until defeated or consumed by another effect. You can recognize them by the polygonal shape of their internal card frame. Units have individual Attack and Life pools, which can be further enhanced or reduced through several means.
This is a Unit. Note that it comes with a "Drum Up" Spell attached to it.
Spells are instantaneous effects that can alter the battle in a number of ways. They can, for instance, provide a permanent enhancement to a Unit’s Attack or Life, destroy or dust Units immediately, summon several Units at once, provide Life to your Hero, damage specific targets, etc. Once cast, Spells usually go to your discard pile.
This is a Spell. Use it to turn the tide of the match.
Enchants are unique, in that they are only ever found attached to (enchanting) Units or Heroes, and have an effect on the Unit or Hero they are ‘enchanting’ - For example, the Enchant Roots prevents its enchanted character from attacking, and the Enchant Shield will protect its enchanted unit from damage.