"Eternal Blizzard" is cast every 30 seconds on a random target. If you drop below 40% health with this debuff on, you get hit with "Deep Freeze".
The Evanescent Coronach spawns in the far western area of the zone. Its three PHs are "a fading dirge" in the area outside the zone to the Wakening Land.
Location for your "kaelshard.txt" map file (note for all known Kael named spawn locations, see this quest entry):