Faction rank is very well covered so that we can buy it at the faction shop. To increase faction rank, faction points are required. Here are some ways to get faction points
Defeating monster in specific area such as razorwing rivine, highland necropolis. But you have to be careful because many opponents are farming faction points in the area.
faction war. Join war and get lot of points (15 k – 20k faction points).
Using faction orb.You can get faction orb from clan shop, timed mission weekly prizes. Hunt Faction points from monsters on the necropolis map (lv140).
Box from conquest mission prizes (in the Higland Necropolis) or can be dropped from monsters in Highland Necropolis, the Ravine Ravine, Stillbrook Basin.