"The blood shall be a sign for you on the houses where you live; and when I see the blood I will pass over you, and no plague will befall you to destroy you when I strike the land..."
Each army has exactly one playable career for each archetype (see table), and each archetype performs a specific main role, although different careers of the same archetype may play slightly differently. For instance the Sorceress is a Ranged DPS archetype career, however, her play mechanic (called "Dark Magic" - causing her to have a chance to hurt herself the more harmful magic she casts) is very different from the Shadow Warrior (also a Ranged DPS), who has a stance-based mechanic of gameplay.
Archetypes also have an advantage over another Archetype. This plays in very well when balancing the careers.