Your rotation should be:
Raging strikes
Bio2
Miasma
Bio
Swiftcast shadowflare
Contagion
Fester
Spam Ruin/ruin2
Fester
Raging strikes goes off
Then u continue with Ruin until you need to refresh your dots. Use fester and refresh aetherflow.
Use rouse+spur (not in gcd) when possibile and depending on how much damage you need to do use Enkindle (for example when u need to push dps rouse/spur/Enkindle is powerful).
In t7: keep Garuda on Melusine or it will kill the renauds. Refresh your dots and fester melusine and the Lamias.
Take the renaud with ruin2 and when they are in position use miasma. Then, focus again on Melusine or the adds.


Remember that the potency of your dots is influenced by the buff you have before you cast them. If you need to use a x potion of intelligence be sure that u have contagion up.