My latest fun came from the fortress of (really long name coming from randomly scrolling down the wordlist and whatever word I stop at is part of the name.). I decided to try my hand at an evil embark and lo it was a story the bards will sing about for ages to come, atleast the bad bards, on whom people throw shoes until they sing something better.
The great fortress was founded by venerable and respectable dwarves from high standing families, dwarven society had grown tired of their respectability and venerable...ness? and decided to ship them off to the middle of nowhere.
Not a cliff in sight there was only one thing to do, dig down, the first layer contained the farm and foodstocks of these fine dwarves and the second layer contained the luxury barracks and workshops, all in nice easy to clean sand. The third level contained a dining hall and what was to become a secondary living area, but all too soon became a graveyard.
The first priority after getting basic functionality out of the fort was to prepare some defenses, a long corridor of walls was erected around the entrance and it would be filled with traps to deal with what I expected to come in this evil biome, kobolds, zombie kobolds, dragons riding zombie kobolds, vampire dragons riding zombie kobold lashers and the like.
Only, nothing dangerous seemed to come, I saw some sloths and armadillos and a few bumblebees here and there but nothing that would cause any trouble my wardogs could not deal with. Things were progressing steadily and a few migrant waves arrived, some trade caravans who ripped us off and a few armadillo incursions.
Then suddenly I noticed blood, cat blood everywhere. Curious I checked my cats but I could see no wounds on them so that made me suspicious. It was at this time I started getting clouds of dust drifting in over the fort, I laughed in the face of these clouds as I ordered my dwarves indoors any time it seemed one of them would get close.
Was this the forst this evil place could throw at me?
Then shit hit the fan.
A dwarven caravan arrived and as they were standing in the trade depot a cloud appeared, quickly I ordered my dwarves inside but the caravan decided to tough it out, as did my wardogs. Soon I had a caravan full of free stuff and a nice pile of rotting dogs to greet any travelers. Dreading the risk of ghosts appearing I quickly converted by secondary dwelling area to a mausoleum and started producing coffins, only my carpenter seemed to decide this was a perfect time to go on a break of undefined length throwing party after party after party in the dining hall.
Some time passed and my fort was now full of ghosts harassing my poor dwarves and tragedy would strike again, finally having coffins ready to bury the visiting traders I ordered my dwarves to go pick em up from the temporary resting place (a pile next to a pile of dead rats), only to be struck by another cloud. Only four dwarves remaining now I decided to implement the secret "Flood the fortress from the nearby river"-plan so the fort would atleast be safe from grave plunderers. A channel was dug from my entrance to the river and a brave dwarf got the honour of digging through the last dirt tile.
Physics did not work in my favour though as the water flooded down the stairs... and down the stairs.. and into the first cavern layer I had recently uncovered, probably causing some poor forgotten beast to call his landlord complaining about the leaky roof.
Well my dwarves would die of drowning if it was the last thing I did so a few caveins and channels later my fort finally started flooding. Only it seems my dwarves were actually mer-dwarves, they continued working like normally even saying they were soothed by a waterfall lately, even though they had ghosts haunting them, dead friends and water to their beards they were actually extatic.
Well screw this I said and designated the entire river to be dug out thinking this would surely drown them... but they went about it like it was a sane demand and actually stood in the river, under water, digging... and not dieing?
The last season came and the fort attracted no migrants from the sissy mountainhomes, what? a few ghosts, a pile of dead dogs and a little water is not good enough for you? Eventually after throwing parties like madmen in the flooded dining hall and soon running out of food I ordered my dwarves to go wrestle the last armadillo not to be killed by the now constant clouds. And thus was the end of the fort sealed.
tldr version: Evil biome, clouds, mer-dwarves and dogpiles.