Combo Action Button

[Rongway]

Now that I think of it, I wonder if a macro of f4 + b4 + enochian would work...

"Yes", but no.

/ac "Fire IV"
/ac "Blizzard IV"
/ac Enochian

would do what you want, but you would have to press the button after the GCD finished, so you would lose 0.1~0.5 seconds per cast, which quickly adds up to multiple Fire IV spells lost over the course of a battle. And if you mashed the button trying to get it to fire ASAP, you would at some point trip the Enochian line in the middle of a GCD, which could potentially delay your next GCD by as much as 0.7s if Enochian comes off cooldown just before the GCD finishes.

So "yes", but no.