“ The characters are wandering through the bustling crowds of Lasopolis. A street conjuror is performing a simple summoning spell, something for the kiddies. A bit of odious purple powder in the fire, an incantation and out pops a saak-lizard or a muhmentarsh, writhing from the flaming brazier. But the conjuror has only a poor grasp of the arcane magical tongue. A few stuttered syllables could lead to Other Things coming through the brazier and giving the crowd more entertainment than they had paid for...”
“ 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.”