Either castsequence if you wanna do multiple spells, or just mash one nukebutton.
Mainnukes for mage while levelling:
Fireball - 3.5-3.0 sec cast
Scorch - 1.5 sec cast
Frostbolt - 3.0 - 2.5 sec cast
-
Shaman:
Lightning Bolt - 2.5 - 2.0 sec cast
(on rotation and with CD)
Chain Lightning - 2.0 - 1.5 sec cast (6sec cooldown)
So, what you _could_ do, is using talented Frostbolt and non-talented Lightning Bolt, but that's just silly imo, you want Lightning mastery for other obvious choices as well.


Frost gives you more time before the mob reaches you, fire is more dmg output by itself. Arcane/fire and arcane/frost are builds that supplement eachother pretty well.
EDIT: Offtopic: wanna share some about your dual melee team? How you did it and all?