December 2011 Army List Challenge

This is the final Army List Challenge of the year!  And this time, its personal!

The basic question and theme is this: what army list do you most fear facing?  Why? 

Perhaps it is a list designed to take down your own, most regularly used list?  Perhaps they're simply too quick?  Perhaps there's just too many grots for you to shoot at?  Perhaps your favourite army has a general, irrational fear of soulless silver robots? 

Here's the rules.
(1) Design an army list that you most fear to take on.  There is no points value, but we'll assume its the equivalent to whatever your regular army list totals.  Explain why you fear that list (perhaps by posting your own favourite army list that is going up against it) and detailing what's up.
(2) Post your army list(s) as a comment to this posting.
(3) Entries close at 01:00 GMT on December 14th.
(4) On that same day, I'll open a poll for Warpstone Flux readers to judge which army list they consider to be the "most effective army list that also best articulates the theme" (whatever readers interpret that to mean) out of all entrants.
(5) The winner will be tallied and announced on December 21st (and entered in to the hall of fame!).
(6) One entry per person please.

Good luck!