Chief Caster is usually selected among Casters by the virtue of highest level. However, Casters of lower levels are sometimes installed as Chief Casters (for example, Wanda Firebaugh replaced Delphie Temple as Chief Caster of Goodminton by order of Overlord Firebaugh despite being of lower level than Delphie).
Chief Caster can issue orders to other Casters, which they must obey, although orders of Ruler and Chief Warlord supercede those of Chief Caster. In most Sides Rulers or Chief Warlords supervise the use of Casters and the position of Chief Caster is more of a honorary title. However, in exceptional cases (e.g. in case of Goodminton) Chief Caster can determine the strategy for use of magic and set orders to Casters.