I wanted to use this concept when I get a group of players strong enough. The story is derived from the bible. When the Isrealites wandered the desert for 40 days after their exodus from Egypt they were cared for by the lord with a substance called Manna that rained down from the heavens (They actually just woke up to find it everywhere). While I originally got the idea from watching Ancient Aliens, where by they explained Manna being produced by a machine that could have supplied the people with a food source provided by an extra terrestrial race, i am not taking the E.T. approach (so don't worry).
I was considering making a device (a relic that would require an epic quest) that is able to convert Regio into Vis over time that would cause it to rain down as stones attuned to a certain Form or Technique. This discovery has the potential for limitless Vis sources...but the effects on the environment are unknown and potentially catostrophic. Nothing like this has ever been known to exist, it could open a rift, or cause rampant destruction. It may taint an aura Infernal by causing an unnatural change with adverse effects or may only work in Divine auras (Since this was taken from the bible).
I wanted to tempt the players with power, but when they attain it, more problems arise. Perhaps there was a reason it was forgotten?
The only thing I have trouble with is that I am new, and don't know how to work out the mechanics just right, if anyone else is interested, please feel free to share ideas. I'll be posting mine shortly.
I've seen the animated contraptions of posthumous magi used as vis sources in at least three of my games, so in that respect the idea doesn't strike me as unusual.
I'm now imagining inflicting a rego / muto vim spell on an entire regio with a continuous magic item in order to achieve your vis dreams. My first thought when considering constant duration enchanted devices is naturally warping. The regio isn't a magical creature, it's a natural place, it can get warped.
My second thought is if you design an item per normal rules (with two uses per day, environmental trigger, and duration sun) then a solar eclipse is going to provide an opportunity of the land to be free of the item's magic from the time of the eclipse until sunset, if you count an eclipse as a sunset - which is debatable, but perhaps ancient artifacts worked on mildly different principles than Bonisagian magic. (I'm not sure how you'd use this but I think with a sufficiently warped area a period of non manipulation would be excitingly catastrophic just for story reasons)
How about the regio and its inhabitants become more and more leach-like, blood sucking , desirous of naturally generative creatures reflecting how the enchantment is drawing out the regio's magical forces, then, after the solar eclipse (don't give your players any hints, if they figure it out themselves that's cool if not then give them some other hints AFTER the item has malfunctioned) the regio boundary is torn asunder by a locust plague of ravenous magical spirits and creatures driven wild by their warping generated thirst for the living.
oooo, I like that. Much more sinister than I originally intended. Gives the chance for things to come to a boil slowly and still have catastrophic effects.
Welcome to the game!
Eh, looks like you may be, after all! 