Abn is a "semi-famous" WoW player that has been at the head of the RBG scene(2100+) for quite some time. Along with Bailamos, he has one of the most active Twitch streams with many followers, usually streaming RBGs.
Having said that, I am not sure if he currently still is streaming or even playing WoW anymore for that matter, due to the ban he receive on Twitch for absolutely tripping BALLS on god knows what, and making himself puke repeatedly(and eating it?) during a Live stream. Pretty hilarious and ridiculous, albeit if he doesn't have a serious drug addiction because that... would not be so funny. Not that I have ever personally faced him, but I hear quite often he runs teams that uses flyhacks, scripts and kickbots to cheat and win. This is not news to anyone in high rated RBGS, nor is he the only infamous leader who does this.
I know Abni (arcane mage) from back in Wrath, we were in the same guild "we met on eharmony" he was a decent mage back when i faced him in wrath Arenas, but no where as amazing a some current R1 mages. He ran Resto drood/Arcane mage in 2s to his titles (which was a kind of cheesy comp). These days, he mostly Runs & streams RBG grps, his grps do get the job done/get some high rating but most ppl who face him in RBGs say little good about his skill level.
Arena wise, yes he does use hacks.
RBG wise, can't tell for sure since i don't run ser RBGs since MoP, but a lot of ppl in RBGs these days use all type of hacks or DDOS