Haunt is now a dps cool down, its not longer part of the "rotation"
Basically, try opening with a dark soul + soul burned soul swap, placing all three dots on. Then throw up your curse of elements, launch a haunt and then spam MG until you have most of your procs. At this point try re-applying your dots (pandemic passive) to get the extended duration with the bonus damage, and then spam MG until your dots need reapplying. Apply haunt as you have soul shards (you won't have anywhere near close to 100% uptime).
It's pretty much just that (a little more complex when you get into the true mechanics of the spec but this is the easy beginners version).