This is awesome
I like the idea of digging in sieges, but it'd be kind of overkill if they came in ambushes imho - by the time ambushes start, most of my forts either have to turtle them, or suffer heavy casualties
but when sieges start the only thing a mature fort has to worry about are ranged enemies in vanilla - even then, only elites, if they liberally use ranged and fortifications
Also @ Meph - digging fb and wall destroying titans/ect would be kind of awesome
but increasing the durability of them seems like a waste
Personally I like epic fights, and making them more durable/powerful would definitely add to that, but then again, I've yet to see a fb during my current fort that doesn't have some kind of b/s secondary ability to kill everything that engages it in melee. If you send you're hardened vets to fight some epic enemy and some of them die because the thing is flat out powerful - no problem hell thats awesome even, but if you're vets rofl stomp the stupid thing, and then every single one dies because it had "poison breath" thats just flat out lame, and would definitely lead me, for one, to using ranged people after trapping it somehow in idk a bridge box trap since that would be childs play to set up - because the pathfinding only checks once - they'll keep moving w/out knowing they've been blocked by a bridge being raised
you can even have 2 sep bridge boxes - with flying forgotten beasts, it pumps magma in, and with non flying, it just has the top open to a shooting gallery
basically if you make them more durable, please remove b/s breaths, or there could be a dwarf/workshop/something that you can use to counteract it's o/pness - training melee is slow yet fun and exciting, but the breath stuff is, like i said, lame
2cents have been given...