I have watched it trioed nin+war+whm, while waiting our turn to pop.
The whm was avg run of the mill, im thinking 15/tic atmas and your 6/tic is a must though. I noticed at time had to cast cures very fast, but nothing to big.
The nin was decked though, lv85 relic and the crit katana was used. He was in usu body most the time, though I know he has full af3+2 also, i didnt spam check him to seel all the swaps. Look like he went full out dd and bypassed eva gear, so I would think killing him faster was more important than staying alive. I know when i have fought him he can do alot, but nothing that a c6 cant cure right away, which is what i noticed.
Hard part is when he does his special and stuff, just kite it and recover. Need movement speed for sure as he is fast, and even then he will be hitting you.
During the fight the war was just procing !! then he went afk and just tped off mobs and come in for a ws when he felt like it. The fight was surprisingly fast, they took it from 70% to dead in like 7 mins, so i figure a 15min fight if you play it safe.
I am sure a brd+whm+nin+war could down it in 10 without much problem, so try get your friends lol.