Where do I report Hackers?

[Handsoff]

I wouldn't be wasting my time here if I wasn't 100% sure this guy in Arena hacked. His character name is Ascendant and he is from Juwol server. He is level 1 and que'd up for arena. He did all his skill chain combinations that pretty much keep me stunned over and over again without any coold downs and I went from 100 - 0 percent in less than 30 seconds.. also his animations were moving so abnormaly fast it looked as if he was speed hacking as well... wish I had screenshotted at the time but I was just shocked the entire time.