Reavers from Firefly...
A shotgun that shoots out spiders instead of shotgun shells.
Putin khuliyo
nuclear bomb - that shit will FUCK YOU UP, oh and if you're lucky enough to survive the start, good luck with radiation sickness, cancer & all that jazz.
Koodledrum - Balnazzar EU - 85 Priest - Retired.
Tyranid flesh borer
Anything that causes people to lose their personalities, or minds, permanently.
a woman with my credit cards.
Lololol, I'd be more scared of Tyranid based weapons, like their "guns". They shoot acid covered worms, that melt through you as they eat through you O.o
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Gosh darnit, you beat me to it....
Nanobots leading to the Grey Goo scenario... Google that and curl up in a ball...
Nuclear Chemical Biological. Nukes come out on top because they destroy the land and make it uninhabitable for almost all life for long periods of time. Chemical can also do this, albeit to a much lesser extent. In general, biological is tailored specifically just to kill humans, however, it is usually a pretty horrible death. Of course, chemical death and radiation sickness are pretty excruciating processes as well.
You're getting exactly what you deserve.
Paranoia, I don't think I really have to explain..