Obtain the Second Key Fragment from an Arcane Container inside Coilfang Reservoir and the Third Key Fragment from an Arcane Container inside Tempest Keep. Return to Khadgar in Shattrath City after you've completed this task.

Chain

Arcane Disturbances / Restless Activity → Contact from Dalaran → Khadgar → Entry Into Karazhan → The Second and Third Fragments → The Master's Touch → Return to Khadgar → The Violet Eye → Assessing the Situation → Keanna's Log → A Demonic Presence → The New Directive