1. Army 4.8-6 seconds prepull
3*. Unholy Blight as your first GCD whilst getting in range of the boss.
4. Summon Gargoyle as your second GCD, preferably macroed with a /startattack.
5. Unholy Frenzy macro with Synapse Springs and Blood Fury if applicable. Only pop this once your GCD from Garg is so as to not waste uptime on anything while on GCD.
6. DnD (or ScS if you know the boss is going to move out of your DnD within the next 10 seconds)
8. From here try to maximise your Death Coil usage as its AP scaling is higher than any that of any other ability's. For extra cheesiness, you can spec into Death Siphon and use it in lieu of Scourge Strike during high AP, as it, too, scales better with AP than ScS does.
*Popping Unholy Blight as your first GCD and getting your diseases up ASAP is completely paramount on the pull. Delaying this by even a few hundred milliseconds can make the difference of tens of thousands of DPS during the first 40 seconds on the encounter.