In the Plane of Fear: A personal guard of Cazic Thule. He does not death touch like the other two.
In Fear Itself (static): Note: For all map points of nameds in Fear Itself (for "thuledream.txt" map files), see this quest entry. Terror's PH is one of the two roaming amygdalans (possibly both) outside the perimeter of the ring of fire. He hits for a max ~12,000.
In Fear Itself (group): Part of the "An Offering to Thule" group mission (see this quest entry for information).
In Fear Itself (raid): Part of the "Cazic's Final Stand" raid event (see this quest entry for event and loot information).