“ An alchemist enchanted his equipment to produce even more powerful alchemical compounds, potions and the like. Unfortunately, it is not well-known that he had different sets of equipment for different processes: If the wrong set of gear is used, the result will invariably fail to function. It's not a cursed item, just something that's hard to figure out.”
“ 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.”
“ There is a certain kind of silver-coloured spider who's bite injects an addictive drug into the person that creates a sense of euphoria. Once bitten the PC has a 50% chance of being addicted to the spider's bite and will carry it around with him or her.Long term use leads to serious injury or death.At first the PC will just seem a bit slower or sleepier then normal.”