* GoddamnedBats: Goblins. Especially if you don't set up lights. You will suddenly find your mine overrun by stack of 20+ goblins.
* GoodBadBugs: If a dwarf is mobbed by a stack of enemies too big for the engine to handle, it pretends combat was never going to happen. A blessing, because if you're that overwhelmed, you've probably been stuck in a death cycle for several turns anyway.