True mage

There is very little that differs yourself from the Art you wield. Mastering the powers of the arcane you transcend limitations that lesser mages consider fundamental rules of the Art.

Prerequisites: 21st level, must be capable of casting 9th-level arcane spells

Innate understanding At 21st level you begin your journey to become user of magic instead of mere spellcaster.
Spellcaster gains the ability to spontaneously cast all 0-level and 1st-level spells from their class list, regardless of whether they prepare spells or cast them spontaneously, as long as they have unexpanded spell slots.
Beguilers, warmages and like, who can expand their spell list through Advanced learning (or similar) ability learn all 0-level and 1st-level spells that ability allows. E.g. Beguiler with this ability learns all wizard/sorcerer 0-level and 1st-level enchantment and illusion spells.
Prepared spellcasters also gain ability to spontaneously cast 1st level spell slots from unprepared or higher-level spell slots.
At 24th level applies to 2nd-level spells, to 3rd-level spells at 27th level and to 4th-level spells at 30th level.

Fast recovery - At 21st level you no longer need to rest to recover spells. Each hour you regain 1 spell level per point of your spellcasting attribute base modifier starting with lowest level spell slots. If your modifier isn't high enough to recover any expanded spell slots (E.g. Wizard with 22 intelligence expanded only 8th level spells.) you regain 1 lowest level expanded spell.
You still recover all your spells as normal in addition to your fast recovery.

Arcane blood - At 24th level it's your magic, not your life, that sustains you existence. You add your Intelligence or Charisma modifier to your hit dice at each level instead of your Constitution modifier to determine how much hp you receive (this applies to hit dice from past levels).
Whenever you are damaged you can expand spell slot to protect yourself from amount of damage equal to spell level times your spellcasting modifier.

Ally of magic At 27th level magic starts to bend rules to help you. Your spells are considered spells, spell-like abilities or supernatural abilities (whichever is the most beneficial) and lose all their caps other than your current caster level. (e.g. With caster level 25th your magic missile spell produced 13 missiles, fireball deals 25d6 points of damage and dispel magic has +25 base bonus to dispel check).
Also spells you cast cannot be dispelled nor suppressed except for by epic spells, artifacts and deities. Time when your spells are suppressed does not count against the suppressed spell's duration.

One with magic At 30th level the magic itself recognizes you as someone important.
Spells you cast no longer need verbal nor somatic components and always achieve maximum possible result (as per Maximize spell feat).
You gain SR equal to 10+your caster level + your spellcasting modifier and you add your spellcasting modifier to your checks to overcome spell resistance. Even greater gods need to roll against that SR.
Also whenever a spell or spell-like ability fails to penetrate you SR by 5 or more you gain temporary HP equal to 5 times the spell level up to your maximum HP. Those temporary hit points disappear after 1 hour. Contrary to standard SR spell devoured is completely negated even if not centered on you.

Immortality: Foundation of magic.
As your power, skills and knowledge grows your flesh, mind and soul become more and more a liability than an asset. In time you allow them to wither and die leaving only your power itself suffusing the cosmos as you become the very fabric of magic. Even when names of worlds that you traveled through in your journey will be forgotten, as long as magic will have its place in minds and hearts of being that inhabit infinite realities you will be there to guide your students and learn along with them.