I used the macro rotation and I think it does not round up to 3s. As soon as I finish casting thunder which is 2.5s casting time, it follows immediately with Miasma, no delay between two skills. I don't know how it is for you but that is how I see it. And I do refresh them all at the same time, the order of skill has been made after I tested different skill's order and by far, that give me 100% uptime on DoTs with no DoTs run-out before it is refreshed.
Make sense Darkstrike, however the downside of it is you can not keep 100% uptime on Bio and Miasma because by the time you come back, the duration has run out like 2-3s before they are re-caster. I don't know which will give more Dps, though. I will give it a try with your rotation.
I don't want to activate Aetherflow in advance because you are full MP at the start? I use it as a mana restore, and Energy drain to keep my mana in check. Why would I want to activate it when my Mp is full and it does not boost my dams at all?
