This ferocious creature has plagued adventurers that enter it’s cave for hundreds of years. No one knows what it gaurds in it’s lair, but rumors of vast wealth continue to draw adventurers to it.
Barrow Dragons is a race of lesser dragons, nearly as small as wyverns or about the size of two oxen, that most often make their abode within dark and dry subterranean lairs.
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.