Update: I've switched my warlock to destro and her output is much more consistent.

This rotation provides a little extra wiggle room in terms of how often it will update immolate. In encounters this should permit some movement/mechanics without dropping immolate. If you are driving from the toon and want a little extra dps, any time you update immolate and it has more than 20 seconds remaining, go ahead and cast a rain of fire.

All of these are sent at once, using isboxer macros
Code:
1:/cast dark soul
2:/cast shadowburn
3:/cast conflagrate
4:/cast chaos bolt
5:/cast reset=target immolate, incinerate, incinerate, incinerate, incinerate