I might be a little late with this achievement, that´s why it is incredibly hard to find a group.
To complete it, you need to disperse all clouds in 10 seconds. The cloud phase begins approx. 45 seconds after starting the boss fight.
Yesterday sunqua peak was daily and I used the lfg-tool for 1,5 hours asking for doing this achievement. With normal groups you just won't get it done (some might say otherwise, but I tried many many times now).
The group filled up to (3/5), but after like 30 minutes people left.
Is anyone here in the same situation and wants to complete the achievement?
Just contact me ingame, I am online almost every evening.