Bold Adventurers the Fountain of Youth awaits your lips….
One day a you are walking on a road to get to a popular city of some sort. All of a sudden you encounter a group of bandits walking towards you looking to start a fight.
The Elven city of Pulca is under siege by a small chaos clan of beastmen. The General of the beastman is a shaman that is attempting to open a warp gate from the the Choas realm. If by any chance the gate is opened many many choatic deamons and abominations will be turned loose on the grand Elvish City of Pulca.
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.