He spawned an headed towards me (lvl 75 druid). He was lvl 76 and agro'd stuff so time to evac. When I went back down.. found him after he dropped down the waterfall. Was able to root / rot him.. easy kill. not summon.
this guy is spawned as part of earthy extermination 3 and will appear in the flooded caves area. if you perchance cannot locate him, he will end up roaming around the stream past the caves. he will not disappear if you zone out or anything like that.
i fought him under the water in the stream. for kicks i tried rooting him and was a bit surprised to see him get rooted. followed by snare. then he died.
this guy is easier to kill than the regularly spawns. no special attacks, no extra hp.