“ Arune Spheres
Arune Spheres are hollow, blue reflective metallic spheres about 25 cm/ 10' in diameter (though some are larger). They are made of a thickish glass mirrored on the inside. When magical energies are flowed through the sphere, it produces a haunting tone, which can be varied by the type, intensity, and harmonics of energies passed through it. (It sounds like an electronic organ.) If multiple energy flows are generated, multiple sounds can be generated, some of which sound like mundane instruments. Masters of The Craft can replicate almost any sound in their memory with one. Though originally used as a training tools for those with The Power, it has been adapted to be a musical instrument. All it takes is someone with patience, medative training, and a touch of the Power, to use it. (Thus becoming the favorite instrument of anyone who was tested to the first level of the Craft, but failed to advance).”
“ It is said by the village gray beards Of Breen, that the band of human exiles who founded their prosperous farming settelment almost a century ago,had to fight a long,savage struggle with the original inhabitants of the fertile valley;monstrous trolls that saw the new arrivals as meals, rather than as potential neighbours.After 5 long years, the humans with their superior steel weapons, drove the troll tribe into the bleak highlands and hills sourounding the valley.But as time passed, the old tale begun to become legend, rather than history and is regarded by most, as a mere story used by parents to frighten disobediant children.And yet the village leaders have always forbidden their people from wandering the hills....”
“ 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...”