I am not entirely satisfied by my answers to Is it possible to achieve 9th level spells in 3 different progressions? since one requires treating a divine spellcasting class as arcane by using Alternate Source Spell, an interaction I find dubious by RAW, and the other relies on leveling up during the very short window provided by divine power and locks us into divine crusader for one of our progressions.
To get around these issues, I would like to use an arcane base class instead of sublime chord while still using ur-priest rather than divine crusader. In order to accomplish the required triple-9s, that means starting ur-priest at 3rd level. That means by 2nd level, I need a +3 base Fortitude save (and Will save but that part’s easy).
The ideal start to this build is a level in druid and then a level in wizard: that qualifies me for the blighter prestige class, and then allows me to progress wizard up to its 9th-level spells (just barely) by 20th. Sha’ir or wu jen would also work. A class that gets 9th-level spells by 18th level, like beguiler, dread necromancer, sorcerer, or warmage, misses out, but I could ditch the druid level and blighter in favor of getting that 18th effective level and using divine crusader instead of blighter.
But the problem is that none of those arcane classes have a good Fort save, so even when I take a level of druid (which does), and even when I use fractional saves, that only gets me to a +2⅚ base Fort bonus, which while frustratingly close to +3, is definitely not +3.
So I am looking for one of two things:
A base class with good Fort and Will saves, and gets 9th-level arcane spells by 18th at the latest. I am almost-certain this doesn’t exist, but it would work.
Some kind of way to cheese a higher base save bonus than my classes otherwise offer. Since this is in answer to the linked question the same restriction applies:
Prestige classes allowed from any 3.5 official publication, including dragon magazine. Assume fractional stat advancement (save, BAB), alignment changes as you see fit,
Forbidden: 3.5 FAQ, negative level shedding, pun-pun, DCFS, Unearthed Arcana.