A magical reservoir of spell energy is bound into a special matrix in a guarded vault on a sublevel of the guild or order. Using his guild focus, a mage of the guild "call" spells from this common resource as needed.
Calling a Spell: Calling a spell from the Spellpool can be done at any distance but requires the caster to have an open, unused spell slot of the appropriate level. Wizards preparing spells for the day decide at that time whether to leave some spell slots open. A spellcaster can call only for a spell of a level that he could normally cast. He can call a number of spells per day whose total levels are equal to or less than half his caster level (round down, minimum one). For example, Turial Edemont, a 5th-level wizard/4th-level mage of the Arcane Order can call one 4th-level spell per day, two 2nd-level spells per day, or any other combination of spells whose levels do not exceed four, assuming he has slots available and his Spellpool debt isn't too high (see below).
When a caster calls a spell, he takes a full-round action to concentrate on his focus (which provokes attacks of opportunity). The spell appears in the caster's mind at the beginning of his next turn and can be used immediately. However, if he does not cast the called spell within a number of minutes equal to his caster level, it fades from his mind as though cast. A wizard cannot learn a called spell, despite its temporary presence in his consciousness, though of course he could later attempt to learn the spell through standard means.
Spell Availability: Three stages of access to the Spellpool exist. A member first joining the Order gains Spellpool I privileges, which grants access to spells of 1st to 3rd level. Spellpool II allows access to 4th- to 6th-level spells, and Spellpool III grants access to 7th- to 9th-level spells. No 0-level spells are available, but the Spellpool can provide any other spell on the wizard/sorcerer spell list in the Player's Handbook, as well as any additional spells designated by the DM.
Spellpool Debt: Every time a spellcaster calls a spell, he incurs a debt. He must return an "energy packet" to the Spellpool: a spell he has prepared of a level equal level to that of the called spell, or a number of spells whose combined levels equal the level of the called spell. For instance, the Spellpool debt for a 5th-level spell is five levels, which could be paid off with another 5th-level spell or any combination of spells whose levels total five. Returning a spell is a full-round action, like calling a spell, and depletes a prepared spell slot as if the spell had been cast.
The debt must be repaid within a number of days equal to the character's class level; otherwise, the mage's access to the Spellpool is automatically suspended. Once the debt is repaid, a suspended caster immediately regains access to the Spellpool - except that failure to pay off a debt within one year results in a spellcaster's expulsion from the Order. A mage can't run a "positive balance" with the Spellpool, paying off a debt before incurring it.
For the Arcane Order: The regents set the Arcane Order's rules and policies, meeting each month in the Council of Regents. A regent must attend six council meetings in one year or be removed from the council and lose his regent status (he loses no other benefits of guild membership, nor does he lose his level in the prestige class). Enacting new policies or eradicating old ones requires a three-fifths majority vote to pass.
Generally, the council hands out commissions for lower-level mages of the Arcane Order to perform on behalf of the guild. An individual regent might also head up a special group of lower-level members to accomplish a specific goal, such as investigating a crime committed using magic, undertaking an archaeological dig of an ancient site of wizardry, or some other important task.