Currently, i'm using 31.13 to set up a good defence (since i'm too lazy to just disable invaders manually in the latest version
). I've got 3 squads training, but hopefully i'll never need them (aside from Justice*).
Anyhow, what i have, is, there's my main passageway, then there's a 1-tile-wide passageway off to the side, which has an Upright Spear trap (linked to a lever, of course) at it's entrance, and is lined with Weapon Traps further in. In a siege, i'll raise a bridge to fully block off my Dwarves. I have a chained-up Saltwater Crocodile at the end of the passageway, so the invaders will instead go for that. Assuming any survive the traps (all loaded with the full 10 weapons each), they'll still have an angry Croc to deal with. I'm considering putting that Lion i have in there as well, just because. Don't ever say the Elves are useless, they bring awesome animals to kill people with.
* Also, yeah, this reminds me: So, 99.9% of my trading exports are stone crafts. Gets rid of stone, and puts the Stonecrafters to use. Anyhow, my Baron (First time i've ever made it to Baron \o/) decides to ban the export of Earrings. My Stonecrafter is Legendary due to making an Artifact, so it's not like i'm ever at a loss for crafts, so the ban doesn't hurt really. The problem is, he put the ban out while the Traders were still on the map (they were on their way outta here, but hadn't gotten to the edge etc.), and 3 of my Dwarves got charged with violation blah blah blah. Anyhow, since i didn't have Cages or Chains set up, 2 of the 3 Dwarves were beaten instead. The 3rd was my Captain of the Guard, who was sentenced to time in a Cage or whatever. For whatever reason, he was safe from that, untill a little while later. I don't know if it was because i put some recruits in the Captain's Squad a couple minutes before or something, but i turned my back for like 20 seconds to go to the toilet, and i come back to find the Captain's been struck down. I'm like "AW HECK NAW", so i look at the Combat reports. Appearently a recruit (dunno if it was one from the Captin's squad) stabbed the Captain to death with a spear. The recruit didn't get charged with anything, so i guess it was a beating in leiu(sp?) of the jail time. Fine, whatever, BUT WITH A SPEAR? YOU HAD TO USE A F***ING SPEAR?