The Red Cap of legend, as described in Brigg's An Encyclopedia of Fairie is a short, old man, who captures and kills travelers, then re-dying his red cap in their blood. He has thin arms and taloned fingers, with a pikestaff carried in the left hand. The red-cap's of Mage exhibit all of these attributes, although they wear green overcoats, rather than the blue one that the Red Cap is described as wearing. The Red-cap's leader in Mage (appearing in chapter 15) carries a pikestaff in his left hand.
Red Cap's of Legend can be banished by the showing of a cross, at which he will disappear, leaving one of his teeth behind. The Red-caps of Mage react similarly to adverse situations, as when Edsel hits one with the bat in chapter 9. The Red-caps leave behind a tooth, and an extra earthly item: his pants.
The major difference between the Red Cap of legend and the Red-caps of Mage is that Red Cap is a singe man, living in a tower, while Red-caps of Mage travel in troops. Trooping is actually an attribute of the trooping faeries. William Alington describes them in a poem: "Wee folk, good folk, trooping all together, / Green jacket, red cap and white owl's feather" (Briggs, 109). Unlike Red Cap of legend, trooping fairies wear green coats, as do the Red-caps of Mage.
The trooping fairies fire arrows that cause "elf-shot" in people. Red-caps in Mage use a sling shot and fire what Mirth calls elf-bolts. "It's not quite Grackleflint venom, but it just might muss you up fairly well" (Wagner, 6:3). Grackleflint venom causes a reaction in Kevin in chapter 12 that is an affliction identical in description to elf-shot: a stroke, a paralytic seizure. Another type of fairies similar to the Red-caps of Mage are the Lil' Fellas. They also wear green coats and red caps, and although they do not travel in such numbers as the trooping fairies, they do use and ride hunting dogs which they clad in green, blue, or red. The Red-cap leader of Mage rides a blue clad steed when he battles Kevin in chapter 15.
A creature called the Leanhaun Sidhe appears in both chapters 7 and 15. The Leanhaun is described as a succubus, seducing its host by hypnosis and then sucking its blood until the hosts death. A Succubus, described in Monster Manual by Gary Gygax, is:
The Umbra Sprite has an opportunity to capture Kevin in chapter 10 of Mage. As he puts it he needs "something to lure him, something to subdue him, and something to bind him" (Wagner, 10:11). He sends a will-o-the-wisp to lure Kevin. The wisp is a small ball of light and it is so intriguing, and perhaps hypnotic, that one tends to follow it. The wisps of legend were mystical creatures that would lure unwary travelers to the edge of a pit, quicksand or other danger, and then extinguish their light. Gary Gygax's Monster Manual says that "a victim trapped by these hazards feeds the will-o-wisp as it (the victim) expires, for the thing feeds upon the fleeing life force." (Gygax 101)
The Umbra Sprite summons what he names as Rhiannon's Bane to bind Kevin. Rhiannon's Bane appears a a huge, hairy arm which emerges from any wall, floor of ceiling. It's strength holds Kevin above a bottomless pit in chapter 13. Rhiannon herself comes from legend (as told in Bulfinch's Mythology) which does not involve King Arthur, but is a part of the Arthurian legends as a whole. Rhiannon leaves a suitor to marry another: one whom she loves. She rears one child, and it is her pride and joy. One evening, while watcher-women were caring for the child during Rhiannon's sleep, the original suitor, Gwawl, contrived to and did steal the child. The watcher-women, in terror of their mistress's rage, killed a dog, smeared the blood of the dog on Rhiannon's hands, placed the bones under her bed, and blamed her for consuming her own child. Rhiannon was sentenced to tell people her story and offer to carry them on her back to the castle from the city gates.
How Gwawl stole the child is not known, but it surely related to a farmer whose foal from his most precious horse was stolen from him every year on May first. One year, the farmer, named Teirnyon, resigned himself to watching the foal. During the night, a great and powerful arm reached into the barn and took hold of the foal. Teirnyon cut the arm off and gave chase to the thief. Not able to catch him, Teirnyon returned to his barn, only to find a babe laying outside his barn door. He took the child, and with his wife, raised him to be his own. As the boy matured, his likeness in looks and manner to Pwyll, Rhiannon's husband, were unmistakable. So Rhiannon was released from her sentence.
Possibly, Rhiannon's Bane was the large creature which contrived to steal Teirnyon's foal. Gwawl may have somehow contracted the creature to steal Rhiannon's babe, and when the creature's arm was separated from it's body, the babe was released from the creature. It is the arm which was cut from the body that the Umbra Sprite summoned, and it is this arm that Kevin eventually rips from a wall.
Cromm Cruich, the Worm of the Mists, appears in Mage twice. First, in human form, he battles and kills Sean. Second, Kevin meets him face to face in his natural form. Kevin notices the small skulls surrounding the dragon in chapter 15:
KEVIN: These skulls are so small.
CRUICH: Innocence never has the chance to grow very old. So it's the blood of babes that has made me so bent.
In a very little known part of the legend of King Arthur, Arthur and his armies stop in the outskirts of Brittany. Arthur hears of a giant, living on top of St. Michael's mount. He would steal children walking on the patch by his cave and devour them. Arthur searches and finds the giant, and once doing so they fight. Exchanging only two blows with their weapons, Arthur and the giant end up wrestling down the mountain. Arthur ends the battle with his dagger. Similarly, after killing the dragon, Kevin finds a cave and upon entering it discovers a giant. The giant introduces himself as Goe-Magot, and convinces Kevin to lay aside his weapon so they can "tumble" (Wagner, 15:32). Kevin wrestles a bit with the giant and finally throws him into the bottomless pit.
As Kevin nears his goal, the top/bottom of the Styx casino, hounds come to taunt him. They appear as a troop of dogs with human heads. The dog's faces are the heads of people Kevin has killed, such as Rashem (a minion of the Umbra Sprite), and people during his life he had an opportunity to save, but didn't. They levitate to him as he climbs up the pit.
The hounds are a combination of many different relating mythical creatures. The Gabriel Hounds come the closest to completely filling the image. They are large dogs with human heads, levitating over houses, foretelling death. But Wagner's pack also shows characteristics of the Seven Whistlers: seven dogs that sing yelping howls, also foretelling death or misfortune. Cwn Annwn, described in An Encyclopedia of Fairies, also relates:
The Welsh hell hounds, something of the same as the Gabriel Ratchets, the Wish Hounds, and the Seven Whistlers. Like these they are death portents, but they do not, as the Devil's Dandy Dogs, do actual destruction.
Sikes in British Goblins (p. 233) (quoted from An Encyclopedia of Fairies) describes their howl, which grows softer as the draw closer. Near at hand they sound like the cry of small beagles, but in the distance their voice is full of wild lamentation. To hear them is taken as certain prognostication of death.
These, combined with the Black Dogs (large shaggy dogs that are the form often taken by human ghosts) create the hounds of Mage. They are the Slaugh: hosts of the unforgiven dead.
The Hunter, which the hounds draw to when Kevin denies them, rides upon a motorcycle and wears stag's horns on his head. In several myths, the dogs leader is the devil himself, but Mage's lends himself more to Odin or Woden. Odin is the leader of the Devil's Dandy Dogs, and also is the chooser of the dead. He is said to hunt human souls, leading his troop of dogs with him. In Dieties and Demigods section on Celtic myth, the Master of the Hunt is described as having "jet black skin and glowing green eyes. His head is crowned by a set of stag antlers and he wears a suit of black leather. The Master never speaks" (31). This description fits the leader of the hound pack in Mage.