Long sieges can be a trial for both sides. For the beseiged especially, finite ammunition supplies always pose a problem - except when the ammunition can reproduce...
“ A group of Mages sought to create an Elixir of Fertility, to deal with the Curse of the Empty Cradle. After acquiring such things as the 'ahem' vigor of a war deity, and the 'ahem' blessing of a forest goddess, the mages almost created the cure. Instead, the vessel of Divine Virility was spilled, and instead of curing sterility, infused the ancient hill with life. The temple and alter rose, becoming a demonic force of life essence and the fecundity of nature.”
“ In one region of a forest, all of the trees are identical, down to the leaves and the twigs. If the PCs carve something into one of the trees, it could mystically propigate until it covered all of the trees, or could vanish since it was not carved into the one true tree.”
“ 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.”