Lore
The Magic of Imarel - by T.A. Saunders ©2009, revision v2.9, 12.16.14
Because of the mistakes of the past, there is an unspoken but generally agreed upon accord between the Shar'Vaire and the Quar'Vess that no other race will be taught the ancient magic of the Asyndi. The destructive potential of these spells is considered too dangerous to be given to Humans who the Quar'Vess and Shar'Vaire firmly believe would obliterate themselves or possibly Imarel with access to such magic. Generally speaking, some Asyndi magic has shared with certain Elvish candidates, but there has yet to be an Elf trusted with knowledge of the Radiance.
Likewise the Elves have only very recently begun sharing the knowledge of their advanced illusionary magic with the Quar'Vess but simply refuse to share it directly with the Shar'Vaire for fear of them unraveling some of the more ancient and grand illusions that hide certain Tallis-Vyss locations from prying eyes. Such magic was the reason the Elves even survived the War of the Eternals and remains a safeguard against similar aggression to this day.
Methods of spell-casting are also tightly monitored. The Asyndi Method of spell-casting is very rarely taught to Elves and to date, there is only one Human alive that knows this method of spell-casting (to wit, she is also the Queen of the Shar'Vaire). Conversely, only Humans use the Sengaardian Method and can with practice can learn the Shei Method.
This does not stop people from trying to steal or teach themselves such knowledge. There is a large black market across Imarel centered solely on acquiring old Shar'Vaire and Sivanoshei magic and getting it into the hands of those who probably should not have it. A very recent example of this practice gone awry was an ancient Shar'Vaire sorcerous plague unleashed in Tashran, that nearly wiped that city and Sundown out for the damage it caused. A Human salvage raid had gone into the Burning Lands and discovered an old Shar'Vaire keep where a spellbook containing the knowledge was found and translated in such a way that the spell could be recreated by Sengaardian spell-casting.
Unfortunately, the translation was not entirely accurate and the spell cost thousands of lives between the two cities. The Sovereign of Anthalas had considered strongly letting the plague wipe out a good portion of the population as a lesson in tampering with such power. Eventually with influence from Farwind, Sovereign Dur'lane relented and assisted in conveying the knowledge required to end the sorcerous plague.