I've touched on this before, but magic in Theryl comes from the Shayta: the ancient enemies of the Divines. It's a heretical power that bends the rules and laws of the world, perverting the natural order that Theryl's deities set it place. To the uninformed, magic can appear chaotic and utterly nonsensical, though there is a sort of structure to it. To those willing to indulge this heretical practice though, magic can loosely be broken down into three categories:
Incantations are primarily used to summon and control monsters. They are spoken in a profane tongue that can be painful to even utter, but those willing to endure the pain can bring forth terrible creatures or even channel the beasts of the underworld through their own bodies. It should be noted, however, the monsters have an instinctual drive to kill humans; thus, one must use an incantation repeatedly to keep the beasts under control, or they run the risk of turning on the summoner.
Sigils are symbols that have the power to apply an unnatural effect within an area. They're a difficult form of magic to use, due to the fact that they often need to be applied in advance and usually hidden from sight. Once a sigil is engraved on a surface, its unique properties slowly take effect. A sigil can force everyone in the surrounding area to sleep, create large-scale illusions, or even empower the caster so long as they remain in the vicinity.
Distortions are the most difficult form of magic to master. They essentially bend the sacred elements of Theryl into a perverse form.
Netherfire: A pale-blue flame that burns the soul of any living thing it touches. If it consumes a victim's soul completely, that person's spirit is forever lost to oblivion.
Bloodbolts: Vicious crimson lightning. Bloodolts don't actually cause physical damage to anything they strike, but instinct bring such intense agony that nearly any living being dies within seconds as a means to escape the pain.
Glassmetal: A strange reflective material more durable that steal. Glassmetal can be summoned into just about any weapon the wielder can envision.
Murkwater: An inky-black substance that pollutes any liquid it comes into contact with. Murkwater spreads rapidly, and cannot be purified unless its caster is killed...
Hollowlight: A strange green energy that can eat through nearly anything it touches, including that which is ethereal. Hollowlight is so named because sorcerers often use it as a form illumination, even though it more-so 'consuming darkness' than actively emitting light.
Swarmshade: A curious pale substance that almost seems to have a mind of its own. Swarmshade numbs the mind and senses of anything it comes into contact with for any period of time, leaving its victims confused and disoriented.
Rotwind: An unnatural wind that, as the name implies, can cause anything it touches to rot and decay. Rotwind must be expelled from the mouth of its caster and leaves a terrible odor in its wake.