I'm having a bit of problems with putting the AoE of a demonology warlock into practical use.
Step 1: I know the theory is to put Corruption on as many targets as possible, keep it up and then Hellfire to build up fury.
Step 2: Then to switch to demonform, use void ray to keep the corruption up while continueing to cast Hellfire (Immolation aura).
Now where it gets impractical for me is the next part... you come out of demonform because your fury got depleted, so you continue to Hellfire in normal form. Usually by the time your corruptions need refreshed I find myself being at perhaps 400 fury or so, so I go back to step 2.
Should I just spam void ray a few times (how many times) and avoid burning my fury on immolation aura when refreshing the corruption unless i'm at fully fury?