Request for macro - Fire opening sequence

Today i use this:
/castsequence reset=120 Rune of Power,Scorch,Fire Blast,Pyroblast,Fire Blast,Pyroblast,Flame On,Fire Blast,Pyroblast,Fire Blast,Pyroblast,Phoenix’s Flames,Pyroblast,Phoenix’s Flames,Pyroblast,Phoenix’s Flames,Pyroblast

Works like a charm. Almost. On this macro I have to press Combustion while Scorch casts.

I want a macro for gse that fires of Combustion and the first fireblast while scorch is cast. The tird time I push the button

Fail Pre Combat Damage Loss is emense …!!