“ 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.”
“ Appearing a small ballista bolt, this bolt' is actually an arrow used by a god from a long-dead pantheon. Some sages theorize it was a weapon crafted by Loki to slay the world tree. Why it was never used escapes them however.
The spear has a divine-level anti-plant effect. When driven into the soil point first, a ever widening circle of destruction radiates out from the point, killing any plant material. Perfect for holding a kingdom's food supply for ransom.
How far it extends depends of course on the GM, of course.”
“ The gold hoops and rings that sailors wear are to throw into the sea if there is a storm. These are bribes to the sea gods to let them live through the storm.”