The city that many adventurers seek to drink from the Fountain of Youth…..
A mystic ruin that is well guarded by the family of Dro’Hizzir a great upper class of Shadow Warriors. This is unknown to everyone except for Dro’Hizzir. Knowledge that is only passed down from his forefathers and ancestors alike. Well underground in the city of Pulca. The entrance is found in Dro’Hizzir’s office in his ancestorial vault (that has riches in it as well). In the back of his vault is a narrow tunnel way big enough to fit a normal man in that leads to a ruin of his dead Ancestors and riches of the deceased.
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.