"Whats this do?" Asked the visting Human.
"That," Dugfar replied. "Is my- Wait! Don’t tou-"
...and with that they were buried alive.
The proud dwarven Captain Dugfar stood atop his mighty machine of magic and stone looking down the mountain they had just emerged from; letting the wind whip his beard over his shoulder… "This is a proud day for the Dwarves!" He bellowed. "...and this is just the start!"
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.