Between a Rock...

Overview
Summary
 * 1) Speak with Whispers Adept.
 * 2) Protect the villages of the Yatendi Canyons from attack. You have 6 Margonite groups left to destroy.
 * 3) See Whispers Adept for your reward.

Obtained from
 * Whispers Acolyte in Chantry of Secrets

Requirements
 * Lightbringer title
 * additional unknown requirement

Reward
 * 4,000 XP
 * 400 Gold
 * 15 Lightbringer Promotion Point

Walkthrough
Pretty straight forward. There are 6 groups of 6-8 enemies, approaching in three waves of two groups. As you will be fighting in one place all the time, wells, wards and traps help a lot.