Prestige class that advances spellcasting but reduces spellcaster level

[redking]

There is a PrC that advances spellcasting/spells known for all ten levels (I think), but imposes three negative spellcaster levels (I think) for all but for one school. I can't remember which PrC does this. Anyone remember?

[Doctor Awkward]

Wild Mage from Complete Arcane permanently reduces your effective caster level by three, and adds the results of a d6 roll to your caster level every time you cast a spell. But that affects all schools. I can't think of anything else similar off of the top of my head.

[Crake]

Unseen seer boosts your divination caster level by 1 every three levels, but you get an equal penalty to caster level to all other schools of magic. Alongside that, you also get full spellcasting progession.

[redking]

Unseen seer boosts your divination caster level by 1 every three levels, but you get an equal penalty to caster level to all other schools of magic. Alongside that, you also get full spellcasting progession.

Unseen Seer is what I was thinking of - thank you.

Is this the only PrC using this kind of mechanic?

[Troacctid]

Prestige bard does something similar.