I was invised running to coth spot to coth guild over to the All-Seeing Eye guy when this thing, which sees invisible pops out from somewhere and starts beating me. He does hit hard. I am lvl 70 GoD-geared mage with a GoD focused-pet. My pet was whacking away at this guy, and I chain casted the mage's highest damaging firebolt (with focus about 3600 damage) and his HP barely went down maybe 6-8%. I had to chain cast pet heal and bolt nuke to get this guy down. He dropped a stupid mask that's no drop. Anyway if you are doing run-to-coth spot alone, if you can't take this dude you may wanna go with more than yourself.
This guy hits pretty hard. Tripples for 600 on a 65 wizzy. I helped him take it. Just me (65 shammy), him (65 wizzy), and his 55 cleric. Cleric went oom after chaining CH's on the wizzy and I laid a couple more tnargs on before we took him down. Not particularly hard if you're expecting it. I don't remember if he mitigated slow or not, but didn't have trouble landing spells after malos.