From Dragon Age Wiki
Hurlock Vanguard Skills
The targeted darkspawn becomes your thrall, serving until death. Up to three thralls can fight at your command simultaneously. If a thrall disappoints you, use this ability on it again to execute the underperformer.
The Vanguard lets out a fearsome cry that gives nearby enemies a penalty to attack. With superiority, nearby enemies are also knocked down unless they pass a physical resistance check.
This character follows up an attack with two hits from the shield, dealing normal damage with each attack. If the target fails a physical resistance check, it is stunned. Shield Mastery doubles the character's strength bonus for each strike.