ok, after correcting my spelling, and some more experimentation... (I moved all the longer cooldowns out for manual casting for now)

Code:
/stopmacro [channeling]
/cast Nether Tempest
/castsequence Arcane Blast,Arcane Blast,Arcane Blast,Arcane Blast
/cast Arcane Missiles
is doing about 18k self buffed in the lvl 86 greens you get from the quest.