we took him down fast with two greater dragons last night. you can also disco the tormented minotors. I did not get a change to try to disco the merk champ due to his stomp attack. Sometimes he does it two times in a row which is insta-death. If you are invis or hidden the stomp attack does not hit you for some reason so stay hidden on anyone you are not using or heal heal hide. Take advantage of the ability to not get hit due to being hidden. I would also consider having a level 6 weaving to cast Gift of Renewal on dragons.
You also cannot area peace merk but u can area peace his tormented minotaurs. It seemed like the tormented minotaurs also have the stomp attack too.
Definitely wear a bovine slayer if you are using a melee approach. I am wondering if getting on a roof with an honor archer is the way to go. the q is will the stomp attack hit you if you are up there. If the answer is no, that is the best way to kill him.
Last night, we ran in had everything chase us out of the building, area peaced which left the tormented minotors behind while merk kept chasing and killed merk first. The question remains does the replica, that falls 33.3% of the time, fall if you do not kill the tormented minotaurs too. If anyone gets one without killing them please post.