I was always guessing, shouldn't it be better to use Bio->bio II->miasma? Bio is instant, and it's the most powerful dot, so why not using it immediately? If you use Bio 2 and miasma before bio use waste those 5 second in casting, while other dds are already attacking the mob/boss, if you use it at the beginning bio is hitting in those 7.5 second(each 3 second i know), so why not? If it's for fester you can ruin 2 after miasma and then use it