Well, i finally struck clowns.
Fortunately, the upright spear/spike traps i set up were in front of the right circus tent, I quickly had exactly 100 clowns on their way to entertain.
However, none of the clowns can make it past my very first set of traps. At all. So far it's clowns:1(Idiot ran all the way downstairs for the 1 adamantine mined out to start it and got killed on the traps holding the clowns back) Dwarves: 22
Edit1: Apparently the first 25 were a distraction to keep me from noticing the others going various other crazy places and bypassing my siege engines entirely. Some went up a magma pipe and are getting put down by the 6 FBs i never bothered with in Cavern 3. Some of them did some ridiculous diagonal-up move(Water can't move in this direction, it is blocked by obsidian) to get into a failed experiment with water and the magma sea and destroyed my web gathering loom(which is worthless now anyway, i got pretty much everything down there, and if any is left, i have so much cloth it's laying around every workshop that ever used it totally packed full), however they still have to get past my 41 war bears and 24 man military.
Edit2: Several dwarves are shambling off towards the depths for no apparent reason, they have no job, everything is forbidden, and yet they keep going. They're quickly struck down by clowns and whatnot, however none of them are particularly important or irreplacable. A legendary engraver went down there, but turned around randomly and went back upstairs. Also a salt fiend punched a war bear's ear off and then his skull through his brain before he could even react.
Clowns:4+1(war animal), Dwarves: about 30 FBs: 6(wtf? they're not really impressive looking, but they are tearing shit up down there)
Edit3: A lone miner looking to put god knows what in a stockpile went ALL the way down to the siege engines, where a lone clown was waiting on him. He obviously fled, and is conveniently leading him under a cave in i had prepared earlier. Seems like a waste to blow it on one clown, however it's not going to cost me anything and it'll just be dangerous looking if i don't use it so i assigned the miner a small tomb in honor of his silly but not entirely useless sacrifice.
Edit4: Pulled the wrong cave in lever, killed all my war animals and all but two of my melee military units. So much for all that prep work. :/
Edit5: cave in caused the game to crash, and the earliest save is just before the start.