NW = North Wind, a Wind Element Ninja Skill -> M. Attack based
DFF = Dragon Fire Formation, a Fire Element Ninja Skill -> M.Attack based as well
FSK = Flying Side Kick, a Star Gladiator (SG) Skill -> More Melee based
There's alot of builds you could possibly run, each one has its pros and cons. These 3 are the most popular ones you'll see in WoE.