I'm not doing competitive arena yet, so I'm just theory at this point. My experience is a bit of BG's but mostly PvE stuff.

I personally use a macro for Thunderstorm, Fire Nova and Fire Elemental that looks something like this:

#show Thunderstorm
/use [mod] 13
/use [mod] 14
/cast [mod] Thunderstorm
/castsequence [nomod] ,,Thunderstorm,

Also have Earthbind and Earth Elementals on rotation, but don't go with anything to drop them all at once like the above spells.

For the most part, Thunderstorm (Knock Back), Earth Bind (Root/Snare) and Fire Nova (Stun) are control options for me, but I do have the option to burst with them...