Speak to Khelden Bremen and purchase the Arcane Missiles ability, then practice casting Arcane Missiles 2 times on a Training Dummy south of the entrance to Northshire Abbey.

Chain

  Beating Them Back! /   Beating Them Back! /   Beating Them Back! /   Beating Them Back! /   Beating Them Back! /   Beating Them Back! /   Beating Them Back! →   Lions for Lambs /   Lions for Lambs /   Lions for Lambs /   Lions for Lambs /   Lions for Lambs /   Lions for Lambs /   Lions for Lambs →   Simple Letter /   Consecrated Letter /   Encrypted Letter /   Hallowed Letter /   Glyphic Letter /   Tainted Letter /   Etched Letter /   Beating Them Back! → Charging into Battle / Immolation / The Deepest Cut / Mastering the Arcane /   The Hunter's Path / The Power of the Light / Healing the Wounded /   Lions for Lambs →   Join the Battle! /   Join the Battle! /   Join the Battle! /   Join the Battle! /   Join the Battle! /   Join the Battle! /   Join the Battle! /   Join the Battle! →   They Sent Assassins /   They Sent Assassins /   They Sent Assassins /   They Sent Assassins /   They Sent Assassins