Asteria

Asteria is a rare prime creature located in Celestion. She appears to be a warrior class and spawns with her two sisters, Acacia and Atethys. Together they drop Pants of the Torine Sisterhood. If they leave combat, any that have been killed will respawn and reset with the other two.

Location
Asteria can be found inside the dungeon located at the top of the Godsbreath Terrace at: (2485, -3148)

Achievement
Killing Asteria is part of the I Like it Rare: Celestion achievement.