From Compendium of Worldly Lore
Sorcerers channel unknowable powers, and wizards are expert in ancient lore, but few individuals have as thorough an understanding and mastery of arcane magic as the ultimate magus. By combining both sorcerous and wizardly abilities into a unified whole, the magus empowers herself in ways even the greatest archmage can't duplicate.
Due to the specific requirements of the ultimate magus, levels in both sorcerer and wizard are the most common method of gaining entry into this class. It might be possible for members of other spellcasting classes to do so under specific conditions, but such an occurrence is as rare as cockatrice teeth.
Role: Spell Utility
Characteristics: The best of both arcane caster world. Arcane theurges with expanded knowledge and power
Source: Complete Mage
Game Rule Information
The Ultimate Magus has the following game statistics.
Abilities: Intelligence and Charisma are the biggest ones as they dictate your casting stats.
Alignment: Any
Hit Die: d4
Starting Gold: N/A
Class Skills
The Ultimate Magus's class skills are Alchemy (Int), Concentration (Con), Craft (Int), Decipher Script (Int), Knowledge (all skills, taken individually) (Int), Listen (Wis), Profession (Wis), Scry (Int), Search (Int), Spellcraft (Int), Spot (Wis), Use Magic Device (Cha).
Skill Points at 1st Level: (2 + Int modifier) × 4
Skill Points at Each Additional Level: 2 + Int modifier
Class Features
All of the following are class features of the Ultimate Magus.
Weapon and Armor Proficiency: A Ultimate Magus is proficient with whatever they were already proficient with prior to taking levels in this class.
Spellcasting: At each level except 1st, 4th, and 7th, you gain new spells per day and an increase in caster level (and spells known, if applicable) as if you had also gained a level in both a prepared arcane casting class and a spontaneous arcane casting class to which you belonged before adding the prestige class level. You do not, however, gain any other benefit a character of those classes would have gained.
At 1st, 4th, and 7th level, you gain new spells per day and an increase in caster level (and spells known, if applicable) as if you had also gained a level in your arcane spellcasting class with the lowest caster level. For example, a 4th-level wizard/1st-level sorcerer who gained one level of ultimate magus would gain increased spellcasting ability as if he had gained a level of sorcerer (since that class's caster level is lower than his wizard caster level). If all your arcane spellcasting classes have equal caster levels, you can apply this benefit to any of your existing arcane spellcasting classes. You do not, however, gain any other benefit a character of those classes would have gained.
Arcane Spell Power Ex: At 1st level, your caster level for all arcane spells increases by 1. It increases again at 4th level, 7th level, and 10th level (to a maximum of +4).
Expanded Spell Knowledge Ex: At 2nd level, you can select one 0th- or 1st-level arcane spell from your spellbook and add it to the list of arcane spells known for a spontaneous casting class, even if you can't yet spontaneously cast spells of that level. (In this case, you would know the spell but wouldn't be able to cast it until you had spell slots of the appropriate level.)
You can add another spell from your spellbook to your list of spells known every two levels thereafter. At 4th level, this can be a 0th-, 1st-, or 2nd-level spell. At 6th level, this can be any spell of 3rd level or lower. At 8th level, this spell can be of 4th level or lower, and at 10th level it can be of 5th level or lower.
Augmented Casting Ex: Starting at 3rd level, you can choose to sacrifice a spell or spell slot from one of your classes to apply the effect of a metamagic feat that you know to a spell cast using another arcane class. (For instance, you could sacrifice a sorcerer slot to apply a metamagic effect to a wizard spell.) This sacrificed spell or slot is lost (just as if you had cast the spell) in addition to the spell you are actually casting.
The level of the spell to be augmented can't exceed 1/2 your class level. For example, when you first gain this ability, you can only apply a metamagic effect to 1st-level spells. A 10th-level ultimate magus can affect spells of 5th level or lower.
The level of the spell slot sacrificed must equal or exceed the spell level adjustment of the metamagic feat. To empower a spell, for example, you would have to spend a 2nd-level or higher spell. You can't use this ability to augment a spell already affected by a metamagic feat.
You can use this ability a number of times per day equal to 3 + 1/2 your class level.
Bonus Feat: At 5th level, and again at 9th level, you can select a bonus metamagic feat for which you meet the prerequisites.