We spent yesterday evening doing Sivara Mythic. Enjoying the fight.
There was one thing that was pretty annoying that happened every few pulls with the tankdebuffs Septic Taint and Rimefrost.
Our tactic was to swap around 7-8 stacks, and that worked great. But some tries, the debuff actually naturally timed out after the boss chained a few casting abilities, creating a pool just by the boss (Not what we want with our tactic) Some tries it never happened, and other it happened 5-6 times. That to me sounds like there is small variations of the spell rotations that change every pull (Jaina spellqueueing but not as extreme).
The solution for now is obviously to keep an eye on the time remaining and basically make a judgement call to tankswap early and dropping the pool if this can happen.
It feels like it's not an intended part of the fight, because it changes the tactics for tanks quite abit dependant on the rotation she happens to choose.
Possible solution might be to make the debuff last a second or two longer? Or always make her do a refresh after cast?