Some of the most powerful and spectacular spells worked across the Realms are cast in the form of circle casting. Circle casting is a type of cooperative spellcasting that allows the spellcaster leading the circle to increase her power significantly and achieve results otherwise unavailable to the spellcasters composing the circle. The Red Wizards of Thay and the Witches of Rashemen make frequent use of circle magic. Stories of other forms of circle magic abound in Faerun.
The ability to participate in circle magic requires special magical training.
One spellcaster, usually the most powerful or experienced character present, stands at the center of the circle. This character is the circle leader. A circle requires a minimum of two participants plus the circle leader. Up to five participants can aid a circle leader in a standard circle, but a more powerful caster can lead a great circle containing up to nine or more participants.
All participants in a circle must stand within 10 feet of the circle leader, who stands in the center.
The first use of circle magic is to empower the circle leader with the strength of all the participants. This requires 1 full hour of uninterrupted concentration on the part of all participants and the circle leader. Each participant casts any single prepared spell, which is consumed by the circle and has no effect other than expending the prepared spell. The spell levels expended by the circle participants are totaled as circle bonus levels. Each bonus level may be used to accomplish the following effects:
- Increase the circle leader's caster level by one for every bonus level expended.
- Add Empower Spell, Maximize Spell, or Heighten Spell metamagic feats to spells currently prepared by the circle leader. Each bonus level counts as one additional spell level required by the application of a metamagic feat to a spell. The circle leader may add the feats listed to a spell even if he does not know the feat or if the addition of the feat would raise the spell level past the circle leader's normal maximum spell level.
- Increase the circle leader's level by one for level checks (dispel checks, caster level checks, and so on) for every bonus level expended (maximum level 40th).
These effects last for-24 hours or until expended. Circle bonus levels may be divided up as the circle leader sees fit.