Hydra? I had to chop all seven heads off to kill it, while it was distracted by my "companions" (read: goblin ambush fodder).
On that note, did you notice how weak and useless the soldiers became? Take 20 of them, go for a while, you get ambushed by 20-30 goblins and you're lucky if anyone of your's survives, let alone not horribly mutilated beyond repair and I'm not even speaking about still having his weapon...
.17 is fucking brutal (and I like it).
I dare to disagree. One of my most successful dwarven demi-god Urist Worthystandards was acompanied by a human axeman Leto, armed with bronze great axe. This guy managed to get most of the kills instead of my dwarf - gloom horror's spouse, troglodyte, 3 goblin chieftains, and some twisted shadow monster, they all fell to him. Most notably, he survived my dwarf, and I bet he continues his rampage.
I think it greatly depends on how armored the recruits are - if they have some iron or bronze on, it extends their life expectancy greatly.
Ad topic - I think hydra's are vulnerable to really large groups of fanatic henchmen. I took 14 people to a quest to kill hydra, and just watched as my troops hacked it to death. It's amazing how they all fight to the death, seeing their comrade being bitten in half. I lost about 5 or 6 people.