Mar 7th 2011 6:34PM At level 85 in demonology spec, the VW can act as a clutch tank for any mob with up to roughly 400k health. (Problim and Tank come to mind.) The trick is the wonderful, wonderful ability called Demon Soul: Voidwalker, which transfers all threat you generate on the mob to the voidwalker for 15 seconds. This makes soloing elites almost fun.
Sick the VW on the mob while you're standing at maximum distance. When the VW reaches the mob, pop DS:V, activate all your cooldowns (Figurine: Jeweled Serpent, Metamorphosis, what have you) and cast away on the mob. When the 15 seconds expire, the VW should have a healthy thread lead (but probably almost dead), and the mob should have less than 20% health left, allowing you to finish it off quickly.