Arcane has worse mobility than Frost, which has worse mobility than Fire. Also, its not hard to pick up Imp. Blink as either Fire or Frost if you had to. But you shouldn't need Imp. Blink at all if you are using 2 gongs in the air phase, which is pretty standard for normal modes - blink by itself is enough to buy you plenty of time for either the 2nd gong or Atramedes to land. This really isn't a fight that needs a specific spec for it.
Eggimann 90 mage Korgath:
http://us.battle.net/wow/en/characte...ggimann/simple