(1/2) The huge stone castle that sunk, upright, in a bog. Entirely submerged, full of all of its belongings (incl.) treasure, plus (more recent) aquatic monsters. Sunk by a spell collapsing an Underdark cavern beneath it, by drow priestesses. Drow sentinels still posted near.
— Ed Greenwood (@TheEdVerse) August 4, 2018
(2/2) Powerful artifact walled into the castle still throbs with magic. They want it gone/want to master it, but don't know how. They'd love it if adventurers blundered in and freed the thing. Then they'd attack the adventurers, and seize it.
— Ed Greenwood (@TheEdVerse) August 4, 2018
Forgot to mention: faint road to the castle still visible, leading into the bog, and the drow sometimes cast spells (illusions of gem-heaped wagons being led along it, down into the bog, by humans) as lures to passing folk.
— Ed Greenwood (@TheEdVerse) August 4, 2018