Ran the solo weekly last night and at first couldn't kill the end boss. He would reset about one second into the fight over and over. I was only able to finish the encounter by switching to my primary ascension class and one shotting him and his adds simultaneously.
There is a thread about this here; the devs know about it and said it will be fixed in the next hotfix. In the meantime, if you are able to kill the adds quickly, you'll then be able to kill Vihgoh. (Another thread started later is here as well.)
Trick is to one-shot whole encounter Dagger storm target adds Any massive PBAoE still kill everything on site - I used etherflash target self
