About tri disaster, i have some thought

In garuda HM, it's obvious that SMN can do pretty much nothing about razor plumes at earlier phase, it seems that bane sometimes can't/unable to spread through all plumes, but to my experiment you're able to tri-disaster binding about 80% of them which prevents them to move near any of the pillars and we have about 20 sec or less to destroy the plumes before they detonate which is within the duration of tri-disaster

so why don't SMN just bind the plumes while all available dps obliterate the remaining 20%, and leave the remaining plumes to their doom ? it should be more effective that way

Haven't tried that though as it just crossed my mind just now, any thoughts ?

For bane it is viable to tone down the dps by reducing DoT by 1 (either miasma or bio its up to you) to avoid getting hate (assuming the tank have decent aggro for each mobs hitting him) not that effective for aetherflow usage but you can do that if you want and also it was kind of waste to have stacking cooldown on aetherflow so sometimes i just do that one thing.

as for starter rotation that end with fester you can use Bio II - Miasma - Thunder - Bio - fester (inbetween GCD cooldown) - ruin/SF and you can also use SF duration as base time to recast your DoT

and ruin II should only be used when you're on the move or if any mobs tries to hitting anyone except for tank else just use ruin

Aetherflow is like an ammunition which must be preserved but its sometime a better option to not have stacking cooldown (ie: not using it for 1 or 2 min while still have some stack left, kind of rare though)

you can also make macro for aether flow

/ac "Aetherflow" <me>
/recast "Aetherflow"

so you know when your Aetherflow will be available, you can click it while channeling if you just want to check the timer.