I had just finished trading with the humans when a forgotten beast showed up in the first cavern. Quadraped of ice with poisonous gas. No problem, we can handle this.
Then about two minutes later (no more than a few days in game) a second FB shows up in the third cavern. A giant eyeless tick with a poisonous bite. Multiple FBs? That's a bit odd, but sure, we can take this guy too.
Dispatch the militia. Pathing problems prevent them from reaching the tick before a group of crundles rip it apart. Kill stealing bastards.
The ice FB meanwhile has decided it's perfectly content chilling at the bottom of a cavern lake where no one can reach it.
Then a third FB arrives. It's a blob of snow in the second caverns. Is there an FB convention I wasn't informed of? It can't have been more than a week or two since the first one showed up at this point.
The snow FB is quickly one shotted before it can make a nuisance of itself. At the same time I've managed to lure the ice FB over to the shore where my troops can reach it. It quickly drags a marksdwarf into the water and kills him but then gets caught up in a tussle with a Swordmaster who appears to be standing on the branches of a tree growing in the water and fighting the FB beneath him.
Then the universe completely lost it's shit.
The game shifted my view up a bunch of levels to let me know my possessed fisherdwarf had begun his construction but was also still showing the fight in the caverns.
After single-handedly shattering every part of it's body the swordmaster
bites the FB and kills it.
Then I was left with this nonsense.
The cavern lake square where the FB died is now water laced with water, smeared with water, splattered with water and coated with water.
So is this normal? I've never seen multiple FBs within such a short time frame before.