Dual Caster 2 costs 900 XP, while Dual Caster 1 costs 450 XP. Note that Dual Casters have one “caster level” for both types of spells – they do not track arcane and divine caster levels separately.
Divine Spells: Dual Caster 2 has a spell list with five spells per level, while Dual Caster 1 has three spells per level. Spell lists are described for each custom class. A Dual Caster’s divine repertoire is equal to the number of spells per level.
Arcane Spells: A Dual Caster’s arcane repertoire is equal to the number of spells per level. Dual Casters do not maintain spellbooks and each arcane spell choice can only be changed by replacing it as per ACKS p. 67. (Note that classes with Dual Caster 1 do not possess any arcane knowledge until 7th level.)
By default, Dual Casters may turn or command undead as a cleric of the same caster level. A class with Dual Caster 2 can exchange Turn Undead for a 1 custom power. Dual Caster 1 can exchange Turn Undead for ½ custom power.