A man is arrested for mass murder and found to be insane. Piles of corpses were found on his property, neatly stacked torsos with the skin peeled off and the limbs removed. The man readily admits the work is his, though he claims he was only chopping down trees, removing their branches, debarking them, and then stacking them to season.
The man may have swung the axe but it was a Druid who caused the delusion. This Druid is still on the loose and likely to repeat the crime. In time he may get more creative in his "punishments."
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.