Lord barghest

Ok so i am confused as the boss because I have many different ways to kill this boss but evey time I fight this boss I only get him only down half hp then that bs overtime cheat hits then I'm dead. I dont understand this fight I am a 176 death with 194dmg like 70 rest a cross the bord and good stats for the rest and still nothing. I also find the clues so know who is the werewolf and I fight the other bosses as well but still nothing I do works, I dont want to be lame and shift the dot to him because I cant shift it that easily. So I dont know what/ or how to fight him? Any advice is better than me losing my mind.