Governments and mega-corporations have found a way to cheat the the system, the Dream Tanks are their most valuable assets.
One of the most common and well recognized SimSense parlors of the Cosmic Era
They say you give up a few things, chasing a dream. In those mists that's the literal truth, for every dream of yours that comes true, a piece of yourself, mind, body, or soul, gets taken by the mist. Worst part is, you won't even know what the cost of your dreams are until you go to leave, and by then you might not even have a mind left to change...
A fragment of the mists of creation, drawn to those desperate to make their dreams come true. Suitable for any magical fantasy setting.
Once one of their number, the eternal outcast wishes to take from the Elves what they hold dearest - their dreams, their past, their future.
Ages past the Woodking fell into a deep and terrible slumber, and from the fever of his dreams and nightmares the wooden dungeon of Limberlost grew.
On a location with numerous webs, and at least one big spider, there is a something inside a cocoon. It is humanoid in shape, still moving. If the heroes free it (not before they kill or drive away the spiders), they meet a ... zombie!
The poor zombie wandered the dungeon alone, and tried to kill a big living creature (= a spider). The spider used the usual treatment, even if this victim did not look tasty. The zombie can be easily killed as any other zombie. It got but several doses of spider-poison, so can be something worth if it is extracted. You can mention to a druid or ranger the fact the spider had no poison anymore.