Just a note painflare is very good if you are about to lose atunement and

1. Target is about to go immune, and fester is on CD.
2. Target has just reappeared, but you do not have time to apply 3 dots.

Also I dunno if anyone has brought it up but you can waste tri-disaster if you fester too quickly (like spam it) right as you cast it.

The dots do apply much faster than bio does, but it still takes about 0.5 seconds or so.