Hmm . . .
I have two warlocks and one is going affliction and the other is destruction so neither will ever get the Felguard . . .
Perhaps I will rethink that
They started by using their Voidwalkers almost excusivly until around level 35 or so when the damage from the voidwalkers was just too low to keep the attention of the monsters. Then I switched to Succubus who delivers a better punch but has not nearly the armor of the Voidwalker. I would just load on the DoTs and then blast away with my wand and about half way through the fight the monster would stop pounding the Succubus (good thing for her) and come after me. But with the Succubuss's great damage output they did little damage to little ole me before they died and if they dis score too many hits I would end the fight with DEath Coil and be good as new.
Then at 45ish I noticed that the succubuss was just not cutting it and switched back to the lesser damage Voidwalker and am once again doing just fine.
I have yet to find a use for that Felhunter
But that Felguard looks so nice . . .