This is Thayvians build... or what I can remember of it anyway.
http://www.wowhead.com/?talent=obxVc0fzxIziZVxGzs00oThis is the build to get a strong critical Pyro Blast with...
The Macro is done like so,
/cast Arcane Power
/cast Presence of Mind
/cast Pyroblast
This build is not bad for PvP or for Raiding... to me its in the middle. I love the damage I can do with him set this way. My highiest critical hit was just over 6k damage. Have fun with it!