I was actually thinking about using Blizzard I then Fire III so its a quicker cast, cheap MP but still gives me the x3 Asteral Fire and then going into the Fire/Firestarter rotation what do you think?

Also thunder i use all the time at the start of every fight including trash, if its 3-4 mobs i thunder them up and then AoE, the more targets with thunder the higher the chance of proc, but i certainly will give you rotations a go!