they represent opposing forces and provide a foundation for Blade & Soul PvP

A weird way to compare it to is Blade & Soul Gold the paradigm shift mechanic of Final Fantasy XIII. Think of each soul as a “type” (like Sentinal, Sabatour, Commando, etc) within a class, and all three types combine to create a unique player character. The best part is players are encouraged to build different soul tree load-outs (kind of like a paradigm shift, but for one single player). Thus, each player will have a load out for tanking, DPS, healing, soloing, traveling, crafting, or whatever. With a level 50 cap, players will have 66 points to spread across the three trees, with hundreds of thousands of ways to customize a character, and thankfully there is a minor respec fee in case someone finds their character not so awesome.

Now, the world of Rift, called Telara, is rife with different factions and groups. When players join up, they have an option to choose one of two factions, Guardians or Defiants. Guardians are people chosen by the gods to impact the world, and they rely upon spiritual and magical actions. Defiants represent the humanist aspect of Telara, a group of people who have come back in time to stop the Guardians and they rely upon technology imbued with magic. Each side has three exclusive races, and while neither side is good nor bad, they represent opposing forces and provide a foundation for PvP (of which there are traditional PvP instances like Capture the Flag).