The wheel is non-contiguous enough in appearance that isolated sections of it appear to be signs, symbols, and figures, arranged in concentric circles. However, the signs are not clearly visible from the edge of the BP, being partially obscured by their own glow. An initiate gains the power to use each rune by walking along the circle described by the space between that rune's ring and the next one in. How many rune circles the initiate gains mastery over is a function of endurance, with the more powerful runes toward the center.
Resistance to the patternwalk is a function of distance and direction with respect to the center, so that walking directly toward the outer edge (taking care to avoid stepping on runes) presents no resistance, while toward the center progressively becomes more and more difficult as you approach it. Walking a circle presents an average amount of resistance, but is still quite draining on one's stamina reserves.
Those who walk the runes are known as sorcerors and priests. The priests have named each rune and associated it with a thought, power, idea, or image. Unlike the other broken patterns which are often only walked once, it is typical for a priest to walk the wheel of runes many times in their lifetime. After each walk they will contemplate the runes that they have acheived and study their useages. The outermost runes constitute linking runes and grammar particles; gaining power over just them does not give the initiate the power to do anything (you can't say anything with a vocabulary consisting of the, and, not, and a bunch of prepositions). The runes are used to many different affects.
In game terms buying Priest of the Wheel of Runes is considered mastery of most of the runes. The lack of some runes is how the BP flaw manifests for this power.
First they can be used to breach the veils and cross shadow. However, an initate can only search for a concept for which they have mastered the vocabulary. By concentrating on the required runes or combination of runes and walking, the priest journeys across shadow toward the destination. Using the runes in this fashion takes concentration, for the runes naturally tend to slide into the next rune on the wheel. If this happens the priest will start walking in a circular path never reaching their destination. In game terms the wheel provides Shadowseek.
Second, the runes can be invoked as a magical defense. The priests of Chiare invoke defense in one of three ways:
Third, the circle can be invoked to provide mystic sight. By calling the complete circle to mind, the priest sees the world through the circle. The runes will glow in response to mystic forces, and the priest interprets the runes. Seeing the circle is an advanced ability. In game terms the wheel provides a Power Lens.
In addition to the power over shadow granted by the wheel, the priests have devised spells. Highly formalized rotes based on invoking a certain combination of runes. Again a priest is limited in what spells he can cast by the runes he has mastered. The Wheel of Runes is not used to rack spells. In game terms buy Ritual Magic, but not Sorcery.
In addition, the Wheel of Runes can be used for conjuring. Priests who have walked it's glowing border can sit at its edge, make mental contact with it, and instead of traveling to shadow from the center they can summon something to it's center. Then, control becomes a matter of the priest concentrating on increasing the resistance of the circle to allowing creatures to leave the center. In game terms this allows Conjuration to be done without Shadowmastery, but only at the Wheel or Runes. Some priests learn how to use a draw a copy of the Wheel and conjure from anywhere. In game terms, by Shadowmastery.
The runes may also be used as a divinatory mechanism. For this purpose the runes are carefully marked on stones or enameled plaques. The priest forumulates a question, selects a handful of runes from a bag, and casts them upon the ground. The priest then intrerpets the results. While all priests are taught to read the runes, most priests never develope the gift for reading them well.
Finally, some priests concentrate on specific runes, learning how to release their power quickly and to great affect. In game terms this involves buying Mantic Manipulation and Power Words.