Didn't someone use buffed-up harpies from the Dungeon faction to destroy a Castle on a map with 111 or 112 turns? :C
Diamond ones?
Tvaryna destroyed it.
http://vk.com/video-46631338_165606010
UPD:
Although, it wasn't a Castle after all.
And it wasn't with a "cell" (referring to a specific unit or tactic) :D