Battle Modes (BM) refer to the different play styles which characters can play. Each battle mode allows the character to use the equipment and benefits that come with that battle m ode. Battle modes can be selected upon character login, and after the character has embarked on that battle mode. Characters can only play one battle mode at a time.
If you choose your Faction or Devotion BM, you cannot talk to your path mentor, path keeper, use your path set, nor earn path points.