For Amusement's Sake

These Shadow Warriors fight courageously to free their brethren. For amusement's sake, let us goad their fervor. I want you to capture one of their leaders: a Narthain Blade-walker. Look for them at their camp, deep within the forest. To capture the Blade-walker, use this Gem's power upon them. The Phaos Gem was fashioned by Sorceresses of the Dreadblight Convent. You will find that the malevolent sisters have an appetite for cruelty that rivals my own. The Gem drains the will from its victim. Once ensorcelled, the Blade-walker will lose his will to resist.

Find a Narthain Blade-walker deep within Seawind Glade. Target him, open your backpack, and select the quest inventory tab. Right click on the Phaos Gem in your inventory while the Narthain Blade-walker is still targeted. This will mesmerize the Blade-walker making it easier for you to knock him unconscious. Once you have taken him out, return to Overseer Rathus.