same goes for contagion (running with ruda or pet swap opener) if you are unsure of the timing spread a R2 in-between not just like Crimson mentioned for Tri and Fester but even for con & tri beforehand... combined its something like ((Con> (R2>)) Tri> (R2>) Fester

...its heartbreaking if Fester misses or Tri sets without con buff (at least in an opener)... : /