I currently spend most of my time in Heroics and am looking forward to adventure in Epics soon for which I have very limited experience. I'm a little confused when I compare the elemental damage assuming I go Poison between DI's Improved Dragon Breath - Energy Vortex and PA's Carrion Swarm.

While I understand that the Energy Vortex clearly requires deeper investment in a tree, it seems at a glance that it would do significantly more damage than Carrion Swarm and last nearly twice as long. Also, I don't understand how the Carrion Swarm could ever stack 3 times given that the cooldown in the wiki says 6 seconds and it only lasts for 8 seconds.

If I'm poisoned focused, am I better off selecting the Improved Breath option in DI while still selecting the Primal Spell thorn options in PA? Any advice / tips would be appreciated.

My heroics are all about an Alchemist Inquisitor Vile Chemist and I want to play around with the concept of shooting occasionally supported with AOE elemental damage when mobs start to crowd me. This build is just for running R1 difficulty.