Cross Class:
High Priority: Raging Strikes, Swiftcast
Medium Priority: Quelling Strikes
Low Priority: Surecast
Starting Rotation: Raging Strikes -> Bio II -> Miasma -> Bio -> Fester/Contagion (Contagion is a pet ability exclusion to Garuda/Blue carbuncle gained at level 40)->Shadowflare -> Ruin II -> Fester
That should take you the through the Raging Strikes duration
Afterwards you just refresh your DoTs when they have close to no time left (0 or 1 seconds) and optimally never letting them fall off (Shadowflare is also included in this) and Fester/Ruin/Rouse/Spur in the mean time.
So in reality no real "Rotation"
Also, if you're stacked on the enemy you can use miasma II after the first fester before contagion in order to maximize DPS.