Ebon Hawk

Acquisition
Hero Skill Trainers:
 * Shiloh (Sunspear Great Hall)

Skill Trainers:
 * Tohn (Kamadan, Jewel of Istan)
 * Medando (Yohlon Haven)

Trivia
Weakness seems to trigger when foes are casting spells as well.
 * The name of this skill is likely a reference to the Ebon Hawk spaceship of BioWare's Knights of the Old Republic series.