SB = Shadow Bolt
HoG = Hand of Gul'dan
ToC = Touch of Chaos
SF = Soul Fire
CoE = Curse of Elements
Corr = Corruption
Service = Service Felguard
DS= Dark Soul
SFD = Shadow Flame DoT
MC= Molten Core
Pre-pot/SB>HoG>CoE(If no one else provides it)>Corr>Imps>Service>DS>HoG>SF>Meta>Doom
That's the basic opener. With 3036 haste, and 5% raid haste, your GCD is short enough that the 2nd HoG will land while the first SFD is at .2 seconds remaining (If you don't have to CoE, it'll be 1.2 seconds, but there's nothing else with a 1 second GCD you can cast to fill that gap). You'll get a 2 stack like that. Going into Meta immediately following a HoG will cause the HoG that's landing to benefit from Meta, and Meta benefits from SFD, so you end up with a double damage (2 stack) SFD that's buffed by 131% (In my current gear, as a fresh 90 I think it was about 115%). SFD normally ticks for 3.7k without raid buffs. With a double stack and the extra 131%, it ticks for 16.8k.
ToC spam until HoG has 1 second left on its first charge. You should be low on Fury by this point. Pop out of Meta>SF>HoG>Meta>ToC spam. (If for some really odd reason you don't have a Molten Core proc, you can Fel Flame twice. It costs less mana than Soul Fire, and generates the same 30 Fury. If both Crit, it'll even do more damage than SF, but if one doesn't, its less.) At this point, DS should have about 5 seconds left, and that HoG+SF generates just enough Fury for you to ToC 5 more times before DS falls off. Once DS falls, you leave Meta, and start a "conservation phase".
During this, you want to be watching the CD on HoG and DS very closely. HoG is a 15 second CD, so after 8 HoGs, DS will come back off CD. The first one was just used at the tail end of DS, and you want to save the last 2. So, for the next 5 HoGs, this is the rotation.
SF to burn MC procs>SB until HoG is off CD>HoG>Meta>ToC twice>drop Meta>SF to burn MC procs>SB until HoG is off CD>HoG>Meta> etc etc.
Once you hit 30 seconds left on your DS CD, you want to use 1 last HoG. Keep generating Fury after you leave Meta, use Imps as soon as they come off CD (They generate LOADS of Fury, and at 3036 haste, they come off CD after about 1:45). The HoG that comes off CD at :15 seconds, you want to hold. Once you have less that 5 seconds left on your CD for a 2nd HoG stack (5 seconds left on DS CD as well) HoG>SB or SF twice>HoG>DS>Meta>Service. This will give you the 2 stack again, and from there its all rinse and repeat.