This mob spawns at +313, +291, +154 the north end of the zone up against the zonewall to the northwest of Horasug and spawns at 39, 274, 89 in the far NW part of the zone on a ledge with a frozen tree.
I can confirm that he spawns at Loc 39.67,274.16,89.71 in the far NW part of the zone on a ledge with a frozen tree. I killed him today 2/27/2022 & the place holders are the Frigid Cadavers.
Placeholders are the other dwarves in the area--not cadavers. There is one or two cadaver that paths into the area, but they are not a PH. *UPDATE* - Placeholders were changed in a subsequent patch to cadavers.