Took him down once on 8-14-2017. 104 enchanter with tank merc and 101 cleric with melee dps merc.
Killed me first time. He knocks back a whole lot, and mercs don't react well to being knocked back. After some trial and error, I removed the puller role from the enchanter so the tank merc would run back and fight with us. Also had to toggle the mercs stance (both mercs) between passive and aggressive. The dps merc was out of the fight for a long time due to her getting lost after an early knockback. He has about 6.7 million hp according to gamparse. He spawned in the loc given above, he dropped the hammer and sleeves.
Hammer and Glowing Dreadmote today. First try. I guess the RNG was generous because it knows I'm in no hurry. Warrior needs another level before he can use.
Spawned for me on the little peak in the lake slightly off and out from the first land spawn point on the back side of the lake away from the open areas. PH's are easy to find, there's also another one at the head of the lake, NW side, although I've not seen it spawn there. Dropped shoulders for me.