The Fallen Civilization - Mana Sources.
There are 7 'sources' of mana on Alcheryos, at least so far as the World Mage Court is concerned.
1. Pillars of Power, these massive pillars reach deep into the earth, rumors abound that they even reach the heart of the planet. However, no one has been able to reach their base, and the temperature and pressure, as well as the massive magic interference from the pillar itself, eventually overcome all those who have tried. These pillars fill the air with ambient mana, and are covered in mystical runes. Every pillar still active has a city, usually the capital of a nation, or a powerful megalopolis, built on top of it. This allows life to exist within hundreds to even thousands of kilometers in every direction, depending on the leylines, and is an incredible boons to the land. However, there is only a few remaining, as most pillars are but broken husks, buried under the destroyed remains of the cities of the Old World. It is theorized that these pillars were used to provide energy intensive locations with mana, such as industrial hubs and military installations, and otherwise used as a hub for distribution along the leylines, but no one knows for sure. The pillars themselves are covered in runes and positively full of enchantments, but replicating them has completely failed to yield any result, they remain one of the world's greatest mysteries to this day.
2. Mana Springs, these springs of liquid mana appear seemingly randomly throughout the world. They are highly valued, but fairly rare, and most springs tend to have a limited flow of mana, and sometimes dry up, seemingly at random. While mana springs do permit life to thrive within a few kilometers, they are not very good at making large areas livable, hence why most mana springs are called "mana oasis". Some think that the liquid mana from the springs flows from the core of the planet, percolating until it reaches impermeable layers in the rock. They theorize that if some fissures happen in some deep layer of the planetary crust, the liquid mana comes to the surface, akin to how a water oasis can happen by having a breach to underground lakes. Most mana springs have communities and settlements built around them, and serve as a great boon for an economy, as the liquid mana can be directly harvested and sold, without having to go through the complicated steps of condensing ambient mana or liquefying a mana gem.
3. Ley Lines, these gigantic constructs, referred in the old documents as the "Mana Supra-Conductor Planetary Grid", are massive cables, usually tens of meters in width, that snake underground on the entire world. It has been proven, after a series of archeological digs, that they once formed a massive pattern, many hexagons interlocked on the entire world. Most ley lines are destroyed now, shattered by tectonic movement, or by the massive earthquakes caused by the wars of the Great Night. However, those that are close to a pillar of power, or another mana source, appear to power back up, and help spread the mana further. Research into the runes and enchantments inlaid into the ley lines allowed for the creation of the first mana conduits, which are used in modern machinery and large scale ritual patterns. It is thought that ley lines do not technically create mana, but that they just help transport it, even though some are active without any visible source of mana nearby. Historians think that these ley lines used to spread mana to the entire world during the Time of the Gods, which explains why most of the world has not recovered from the Great Night, and is still barren of life. It should be noted that many believe that the ley lines that have access to energy are slowly repairing themselves and bringing the rest of the network back online, but no one is able to confirm it, as ley lines have been placed off limits by the Custodians of the Flame. However, it is a proven fact that the liveable areas around large mana sources, like the pillars of powers, do expand over time, even if the mana output of the source does not change. Wether due to the ley lines spreading it further, producing mana of their own, or another phenomenon is unknown.
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4. Non Linear Reactors, these ancient pieces of technologies, also called "Aether Core Taps" in the old documents, date back to the Time of the Gods. It is said that only the Gods and their closest servants were capable of creating them, and that the knowledge of how to make them was lost when the last remaining Archangels were assassinated during the Great Night. Non Linear Reactors were given their name because, when given a large amount of mana, their mana output grows exponentially. No one has yet found an upper limit to how much mana a single one can generate, however it is known that the quantity of mana required to get past a certain point is impossible to contain (as the NLR does not provide mana storage capabilities, you need something containing enough mana for the full upgrade to transfer it to the NLR). A single Non Linear Reactor can make an area hundreds of kilometers wide habitable, and cover the mana needs of an entire nation. As such, all information about them is jealously guarded, and entire wars involving nations from across the world have sparked when a new one was found. Destroying a NLR is considered one of the greatest crime one can make, up to the level of destroying a pillar of power, and carries a world wide death sentence and bounty ranging in the trillions of mana.
5. Supreme Enchantments, some of which generate their own mana. It is unknown how they do so, and any attempt to crack this secret has failed, usually catastrophically. Some theorize that they generate mana in the same way as NLR cores, but at a fixed rate, as they were only intended to power a specific device or building, not serve as the energy core of entire military installations and starships.
6. Extra Dimensionals, or sentients that somehow had their bodies or consciousnesses transplanted from another plane, are all capable of generating their own mana. This unusual quality makes them powerful individuals, as they can never truly run out of energy, and allows them to constantly generate essence. The more powerful they are, the more mana they generate.
7. Dungeons, who are able not only to create large quantities mana themselves, but also use sapients (or beasts and imbued plants) in their influence field as secondary mana generators. This seems to be akin to how an extra-dimensional generates mana, as it scales with the level of the individual as well. Extremely powerful individuals with the required knowledge can actually turn this to their advantage by tapping into this connection, and harvesting the mana for themselves. This is however extremely dangerous, and rarely attempted with a hostile dungeon, and a dungeon powerful enough could destabilize the connection, and cause a massive mana feedback loop. Technically anything living in a dungeon's area of influence is used to produce more mana (which explains the accelerated growth and evolution of plants and animals in dungeons), but the amount produced is usually negligible for anything but extremely large lifeforms, or very powerful ones (to the level of a beasts or imbued plants).