Arcane Bonus

An Arcane Bonus comes from a spell which provides a bonus to one or more things (skills, to-hits, armor class, etc.) which was cast by an arcane caster, and lays a charge. Arcane Bonuses do not stack with other Arcane Bonuses, even if the two bonuses are attempting to boost totally different character attributes. If a new spell or effect attempts to apply a new Arcane Bonus on a character or creature which already has an existing Arcane Bonus, the subject must immediately choose to either keep their existing Arcane Bonus, or replace it with the new Arcane Bonus.

An Arcane Bonus does stack with a Divine Bonus (as well as any other bonus type, other than another Arcane Bonus), unless the effect being placed upon the target is coming from the same spell as the arcane bonus. This means you can benefit from a buff spell cast by an arcane caster and a different buff spell cast by a divine caster at the same time, even if both spells improve the same attribute (such as armor class), unless both spells share the same name. (Note that 'same name' excludes the parenthetical in the page title, meaning that Stoneskin (Druid Spell) and Stoneskin (Sorcerer/Wizard Spell) are considered the same spell for this purpose.)