“ Coinlake sits perched between two sheer cliffs in the Stigrani range, and is difficult to find, much less approach. Four miles long and two across, the water is a vibrant cyan blue. The lake's shoreline is an unassuming beach of gray pebbles, and its mean depth is seventy feet. The rare times when the sun makes its way between the cliffs and shines over the the still water, one could see clearly the lake's rock-strewn bottom.
Strangely, no fish or aquatic life can be found here.
At night, a peculiar phenomena occurs. When the night sky is clear, the moon and stars are reflected in the lake's surface, but if one were to look at the surface from a high vantage point, the reflection does not match the firmament above!
Instead the water's surface reflects the night sky of some other distant world and seventeen shining golden moons besides, each ones shimmering upon the water like so many gold coins!
Legends whisper that Coinlake is not a lake at all, but a gate or nexus, to some distant alien world.
The mystery has long remained unsolved, and only recently has the Arch-Duke commissioned an expedition to uncover the secret of Coinlake once and for all. Among the team members are several scholars of the Nascent Academy, an astrologer from the Occultists Guild, and of course the PCs, acting as body guards.”
“ A certain type of demon cannot not be hit by ranged weapons or attacks. Attacks have to be made up close and personal for the damage to mean something. Ranged attacks are to impersonal.
Possibally a way to make the ranged attacks more meaningful would be to coat the arrow head or what not with the shooters blood. Of course, they'd better be a good shot, otherwise they're wasting arrows and already bleeding to boot.
Spells: wizards might have half or no effect, preist might work due to divine intention.”
“ With a huge number of sacrificial victims, another realm long ago secretly bound a Prince of the land spirits, Iorstonn by name, thus ensuring the fertility, and improving the magical defences, of their realm. But binding that Prince to one spot has disrupted the weather and magical patterns (ley lines?) over half the continent. Things have become bad enough that a coalition has been formed to rectify the situation, once divinations have established the cause.
Your party is one of the teams assembled to do the rectification: find the binding object and steal it ('so that we can destroy it here in our realm, of course'...*) or destroy it over there. Presumably the Prince will be grateful to his rescuers and angry at the binders, but with a greater spirit like Iorstonn one can never be sure: such beings are 'tricksy'.
* Of course, the rulers of our realm might want to control Iorstonn for their own ends...”