(Players of my upcoming B/X D&D "Dark Karameikos" game should really stay out of this thread.)
(No, seriously, if you're playing in my upcoming game... go no further! For death awaits you all! With nasty, big, pointy teeth!)
Ok, imagine a fantasy world where elves are extinct because the Elvenking was insane and in the olden days got jealous of humans, sequestered all the elves into a huge forest fortress in the hopes the humans would die out, and when they didn't the Elvenking waged war on the humans and lost hardcore.
So, there's this fortress in the woods literally made out of trees (the Elvenking and his elves were powerful arbormancers) that housed the elves for generations of human evolution, and where the few surviving and wounded elves retreated after humans kicked they asses. This is one of the "dungeons" that the PCs can explore.
What types of encounters would you - as a player - think you'd see in such a "dungeon" which would make you say "wow, that was cool"?
I've already got elf ghosts (who will try to enrapture the PCs and keep them there), elf zombies (basically the fortress grew roots into the elves as they were dying to keep them alive, and after the elf died have taken over the body's functions), and devolved elves (those that survived the Elfwar and have resorted to inbreeding and cannibalism).