Terris Thule  

In the Plane of Nightmares:

• Spawns as part of the Hedge event script and is unattackable.

In the Lair of Terris Thule:

• Summons wraith adds at 75%; AE dispells at 50%; activates four gargoyles at 35% (each quad for ~1,100).

In the Plane of Time:

• For event information, see this quest entry. Terris Thule drops three items from her loot table. She has 1.1 million hp.

In Erudin Burning:

• Spawns as part of the group mission The Illuminating Truth.
• Spawns as part of the raid expedition The Torches of Truth.

In Fear Itself:

• Spawns as part of the group mission An Offering to Thule.
• Spawns following the "Cazic's Final Stand" raid (see this quest entry for event and loot information).