Try not to blow aether on energy drains if you were doing that. Unless you need MP, or are in a super short burn period there's not much reason to. Just focus on Fester and bane with them. As for when to use them or how, that's just up to each fight and your playstyle mixed with your group. I could say what I do in each fight, but that doesnt mean it would help you out.

I will say you can get 2 festers off during raging strikes if you weren't already