“Two forgotten places there be- Still and Limbo,
Still where Time is forever Still,
Limbo where Naught is ever Remembered.”
It is taken for granted that medical technologies will advance apace in the future, permitting rapid healing and perhaps even shaping of the human body. This submission is to provide possible flavors for that medicine to come in.
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.