He literally stole our gang yong master's techniques 
Comment by Slay on Gosu - Chapter 119: Season 2 Chapter 33
3 Replies
He was his 4th disciple...
@Sickle shhhh let him vent
@Sickle he is the 1st not 4th, he's the one that the master said had the most internal energy and had mastered all of the clans skills