Just a note for anyone who want to get this achivement. (under Dungeons, Fractal category)
The maximum stack it mentions in the achviement is 19 stacks. Not 20 stacks.
It was a bit confusing at first.
So when it’s near dead, wait for it to block and get stack to 19. Because at 20 stacks, it explodes. Then just kill it while it having 19 stacks.
FYI
ign: Larxene Rakushinu
Incoming Quaggans [iQ]