"Well on the bright side, the other giant lizard monstrosity, the one with the external ribs and poisonous bite, that one seems to be holding its own against the necromantic legions..." says the fish cleaner, "Oh no, wait, that one's undead now as well."
"Och, there's only one way to kill the dead and tha's with fire!"
And such it was the Cutey's Folly arose, a series of intricately mined tunnels to pour magma straight from the volcano into the lower caves to kill off the zombies.
This was a disaster on several unique and horrible levels. First, the magma didn't actually kill the undead, it just set them on fire and encourage the non-flaming ones to spread around the caverns a bit more, creating a more authentic dungeon. The magma flow reduced the moat levels (though not fatally). Further, a scheme to drop an underground lake onto the ever increasing pool of magma in the second cavern layer managed to create a lot of obsidian but failed to staunch the flow.
"Och, it isnae so bad as all that," said Cutey, addressing the fourth wall. "I solved the forgotten beast problem, didnae I?"
Yes, she solved the forgotten beast problem, by turning the forgotten beasts undead and ending them closer to the fort, while marring the cavern layer with magma, water and dangerous blood.
(pictures coming soon)(EDIT 1: it's like half 4 in the morning here and I'm not thinking coherent enough to properly update yet, but in short the upper fortress has a lot of nice flooring, I dropped a second lake into the underground cavern and that solved all the problems and no one important died. Oh, and a giant forgotten mongoose beast managed to get inside the fort by climbing through a hole in a newly dried up lake, but some badass with a crossbow took it down while successfully dodging out of the way of its poisonous breath.)