Maybe the Combustion nerf is not going to happen ....check Dev Watercooler and Ghostcrawler's notes.
"As of this writing, we haven’t made any mechanical changes to Fire, though if you saw any earlier patch notes, we experimented with a few. Long term, we still have concerns about the interplay between Alter Time and Combustion, and we still have concerns about Fire scaling with Critical Strike, but we’re not convinced either of these problems is so egregious that it needs to be fixed in Patch 5.4."
The combustion change wasn't a mechanical change, it was just number tuning, the actual mechanics of combustion remain unchanged after the nerf, it works exactly the same.
I have two rules for the mage forum.
1. Flowers and Sunshine.
2. READ THE STICKIES!