Deep Magic, or Low Magic, is the Creature Magic of the Underground, of Transmutation and Enchantment, or Magical Change. Deep Magic includes Spells of shape-shifting, the Handling of Underground Animalia (conversing with animal/creatures, translating animal/creature behavior, taming animal/creatures), and the Compass of the Underground (the instinctive ability to divine direction in underground mazes and tunnels).

Wizards who weaved low magic in combatant transformed the elements of their current environment into formidable weapons. Boulders could transmute into a temporal dorn beast to chase off attackers, while a handful of peddles could become exploding fire ants.

Deep Magic is also the Magic of the Underground Warrior, and much of it is understood instinctively by fighting races, including the brogmoids. A creature like a brogmoid would never be able to explain why it is he was able to know or do something, but he will know to do it, all the same.

When Yoruk descended into Hades and spent time with Belegur (c. 363~380), their conversations included the Great Mysterious of the Cosmos and an extended session on the topic of Deep Magic, one of the three kinds of magic that flows through the cosmos, and the one that is commonly linked to the dark ways of those who dwell in the underworld.

When Yoruk finally died in 425, his knowledge of Deep Magic was imprinted and retained with his skull. Its bearer wields the knowledge and power of Deep Magic. Thus the crystal Skull of Yoruk has become one of the most coveted and sought after relics in all the Empire.