Shadowknight Spell Strengthen Death

Visit Davorre Bloodthorn in Paineel and undertake the quests he offers.  At the completion of the second quest Experienced Courier, he offers a task to earn the Shadowknight spell Strengthen Death.  He sends you to Rivervale to kill Halfling guards, loot their souls and return the souls to him.  Upon turn in of two souls, he offers the spell as a reward.