“ A supposedly empty desert on the far side of the mountains has started growing. No one knows why. At the center of the desert lies a tall rock outcropping, hundreds of feet tall. Dust storms shroud the outcropping constantly, except for one night a year.”
“ Someone needs the blood of a dragon, given willingly, to make a rare potion. Guess who gets hired to sweet-talk a dragon into giving up some highly powerful blood?”
“ 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.”