When solo, the Felguard makes a great tank, although it loses out to the Voidwalker in terms of armor and health. However, Anguish and a higher DPS makes it generate more threat, allowing it to hold aggro better. Having Demonic Frenzy means that the Felguard gets stronger and stronger (up to 50%) with each damaging attack, and Cleave is a basic attack that can hit multiple opponents -- although care needs to be taken when used in PvE as Cleave can break crowd control. You should key bind Intercept as it can interrupt spellcasting, although it has a minimum 8 yard range so stunning its current target can sometimes be tricky. Think of a Felguard as Warrior lite.