A project to create a number of seeds (acorns or conkers or something) which, if buried, will grow, spreading at an incredible rate, reproducing massively so that it will cover an entire fragment with plant life within a couple of hours, draining the life energy from it and causing it to plummet into the mists. There should be a short delay (half an hour or so) between burial and the emergence of the first shoots, in order to give the planter time to escape. Ideally they would be resistant to fire and lightning, at least to a degree, so that the primary result of attacking them will be an enormous, spreading, forest fire which will burn people to death instead of misting them to death. They will need to be mist-resistant to a reasonable degree so that they will keep the fragment in the mist easily long enough to kill everyone.
Is essentially a fragment nuke, though single-use for the purposes of this project.