Well Summoners already do this,

We're going...

Quickcast+Shadowflare>Tri-Disaster>Contagion (Garuda)>Painflare>Bane>Rouse+Spur+Enkindle (Garuda Aerial Blast)>Painflare>Dreadwyrm Trance>Deathflare (Bahamut TeraFlare)
(Sometimes a little Bliz 2 Spam before the Deathflare)

And all of ours are AoEs that build up to a large powerful AoE in the Deathflare/Teraflare.