A Fighter who follows the teachings of Nen becomes a Nen Master. She can harness the mystical powers of Nen to enhance her already incredible fighting skill, allowing her to shoot bolts of life-draining energy at her foes and to perform superhuman, acrobatic feats. The Nen Master is unique among the Fighter sub-classes, possessing both the physical prowess of a disciplined warrior and the mystical energies of a sorceress. Trained to atune her senses to the natural flow of Nen energy through the universe, she is particularly adept at perceiving the entirety of her surroundings, allowing her to overcome easily any blind spot to which she might fall victim. She can also channel Nen energy into devastating, explosive attacks. Are you ready to witness the power of the Nen Master?(From Nexon website)
A Nen Master is that one fighter who prefers to use magic as much as they use melee.Nen Masters evolve from Fighters. Nen Masters prefer cloth armor , unlike the Nen Master's "sister" subclasses. The cloth , though very weak , is said to not "disrupt" the nen that the Nen Master uses , as Nexon says. The Nen Master can channel the nen they use and use it as a destructive force to annihilate any monster in the way.
Nen Masters also use the most mp out of all the fighter subclasses , but the Nen Master's powers makes up for it , delivering damage quickly and swiftly. Nen Masters also dont take losses lightly , as you heard of the saying , "Revenge is a dish best served cold".