According to Ars Geotia the essence required to fuel magical workings can be tapped by accessing ley lines, as well as by the creation of ‘batteries’ at the confluences of ley lines. Such structures can range from towers to monuments, to ornate structures designed to harness the ambient power. Founts are the rarest of all, often being in very hard to reach and nearly impossible to build locations. These are the wellsprings that feed the ley lines of the world and are countered by the subduction area confluences.
Unfortunately the great work of Atal the Wise is quite incorrect. Atal assumed that the founts and confluences were driven by the rotation of the celestial sphere and drew upon a system of possibly transdimensional viaducts and cisterns, tapping the ambient power of the elemental and outer planes. This has been the standing theory for the last 2700 years, and has been largely unchallenged.
Recent events in the Auchinduin Deep Iron Mine have proved this theory to be lacking in many fundamental ways. The mine itself is rather old, dating back nearly 700 years to its initial founding. It suffered periods of on and off productivity, often laying fallow for decades or even a century at a time. But the iron was always there when the miners returned, but the mine had a bad reputation, and the miners were superstitious about it. (See the Auchinduin Deep Iron Mine submission - note to self)
A structure was unearthed by the constant recent mining of the area. The miners were awestruck by the crystalline massif that seemed to lace itself through the stone. The material is the physical manifestation of raw magic, a deposit created by millennium upon millennium of magical subduction. The massif extends for an unknown depth into the earth, possibly hundreds of feet or deeper. it is angular, but retains a basic pillar shape and is self illuminating. Light dances along the points and crosses in its surface, sometimes discharging as random spells, the most common of which is a weak Stone to Iron spell that replenishes the iron veins in the local vicinity.
The Role of the Clathrates
The Clathrates serve as magical ballast, keeping the balance of the ley lines and such. In areas that draw large amounts of this power soon tap into the heart of the Clathrate, sometimes generating a Clathrate of their own. A hotspot that continually consumes fire aspected essence will develop a ruby Clathrate and will manifest itself as a volcanic site, or a fumarole or hotspring.
On the opposite side, in areas where essence is being produced rather than deposited, such as magic founts, celestially auspicious locations, and the like, the Clathrates act as resevoirs, drawing in the power and storing it in their semi-crystal matrix.
Thus the balance of magic is maintained, making wild magic areas and high and dead magic zones very rare. Magic is ‘safe’ for regular use and stasis is maintained.
Humanity has a powerful effect over its enviroment. The exploitation of magic is common, the overexploitation of magic too is common. The major cities are host to dozens or more sorcerers, guildmage and independent alike. These draw on the magic, and draw and draw. Magic fuels the growth of some of the cities, creating luxuries such as non-flamable light, magical servants, and the casting of fell and evil sorceries. But nothing is returned to the system, the magic is used, and none granted back to the resevoirs. In some places the magic is slightly slower, more difficult as the ley lines are no longer natural flows but instead are sustained by the constant suction of magical power exerted by the magi.
Failure of the Clathrate Matrix
Should a clathrate actually reach a state of decomposition that it collapses, the effect is both immeadiate and all but impossible to ignore. Spells will become very difficult to cast as the ambient flow of essence has been disrupted. Any magic relying on geomancy, or ley lines will completely fail, often leaivng the magus suddenly weakened as the essential collapse will often tap the innate potency of magi. The local area of the clathrate will suffer from a ‘dead magic’ effect, while the periphery of the zone will allow for magic but at greatly reduced levels, as much as 50%, but no more than this.
The ley lines connecting to the other clathrates in the continent will ‘snap’ and cause magic resonance that will cause short term variances in spell casting, and can make thaumavoric, or creatures that subsist on magic irritable or even sick.
given that these structure formed over millenia, is it within the powre of humanity to repair, or even rebuild a clathrate? This is a question that would be related to the tone of theme of your own personal campaign. An optomistic campaign would allow for the structures to be restored by regenerative spell casting, more responcible use of magic, and the repair (burying exposed crystal) of clathrates. A more dark, or sinister setting would deem that the misdeeds of man cannot be atoned for by a few and would follow a downward spiral as the demand for magic collapsed more and more of the structures, permanently damaging, or even destroying the ability to perform magic at all.
My example is that the clathrates cannot be Wished whole again, and since they were depleted and damaged by reckless spellcasting, responcible magic use, and more careful attention to geomancy and landscaping can slowly restore a damaged clathrate. However, this repair takes place on a timescale that is decades leading into centuries long.
Tassite is the technical name of the solidfied structure of a clathrate. It varies in color to match the elemental or celestial aspect of the parent clathrate. It is quite hard and durable, ranges from perfectly clear to cloudy opaque, and is a very good spell reagent. Pieces of tassite can be used to store magical essence like a battery. A wizard can use such an item to boost the power of a cast spell (using more dice, or larger dice) or can use it to cast a spell already cast into it. Natural tassite can be found, but it is so rare that it exists as an oddity, never a commodity.
In addition to the plot hooks provided in the Auchinduin Deep iron Mine…
Wizards, Wizards, everywhere - the secret of Auchinduin has gotten out, and magi, sorcerers, charlatans, and alchemists have come from hundreds of leagues in every direction. The well meaning magi delve into the clathrate, chipping it apart to study its powers and properties. It is discovered that crystallized clathrate is simply an ultimate spell component and can be used for the creation of magic boosting and spell storing magic items. However, this attention causes the clathrate to all but self destruct, leaving the gathered host of magi all but defenceless…
Go Green! - The PCs, being magical and ecologically savvy decide to protect the secret of the clathrate and decide to try and repair the damage done. Can they win a war against incessant and pointless magic use? Is there a chance of winning when the most flagrant abusers are the most wealthly, influential, and potent magi in the kingdom?
Land Grab - upon discovering the structure, a land grab takes place with ambitious lords and nobles seeking to possess the ‘magic mine’ to arm themselves with magic weaponry. Some may do so under the aegis of ‘protecting the mine’ but can they hide the greed in their eyes? The PCs serve as an agent of one such power and are ordered to secure the township, and protect while they bring their greater forces to bear.
Counter Land Grab - not content to play garrison lackey, the PCs decide to take a swing at the crystal themselves, for wealth or power or whatever. The PCs become responcible for destroying a clathrate and collapsing the magical fields across a huge span of land. What would their mothers think?
Animal Planet - A powerful non-human monster (Vychan?) discovers the debacle at the clathrate, and decides to intervene. Why shouldnt it, if we foolish humans muck up the ley lines, it is just a major inconvenience to possibly a collapse of our magic based civilization, whereas such a collapse would cause the permanent death of said thaumavoric creature. Can the PCs thwart the will of a dragon, or can they oppose the holiness of a unicorn?