Rogue/Archivist/Wizard Build Advice?

[Fireblaster3147]

Well, as you can probably tell from the title, I'm not exactly looking for an optimized build. She's a curious soul with a thirst for knowledge from both arcane and divine sources and also acts as kind of a scout/librarian for the team. Any good spells/feats/PrCs I should keep an eye out for? Looking at Unseen Seer and maybe Shadowbane Stalker at the moment.

[Jervis]

If you aren’t going Theurge I feel inclined to warn you that this will be painful. Other than knowledge checks and magic what do you want this character to do? For my money I recommend Rogue 5/Chameleon X since that gives you most of the casting you’re looking for. If you’re an Illumian, which I highly recommend, Lore Delver I’d fantastic but can’t progress two classes. With some DM Fiat you could take a level in mystic Theurge and then progress MT casting with unseen seer, but that’s very high level cheese but in practice isn’t the most broken thing in the system as long as you’re using a OK caster PRC to progress MT casting and not something stupid like Incantrix. For feats I recommend Knowledge Devotion. Great feat. If you’re good aligned then Nymphs Kiss helps with skill points.

[Maat Mons]

Depending on what sorts of shenanigans your DM permits, you might be able to get whatever Wizard spells you want with just Archivist.

If your DM takes a text-over-table interpretation of Rainbow Servant, you can eventually get whatever Cleric spells you want with just Wizard. Though that doesn't kick in until level 15.

Even if you can't get Wizard spells with just Archivist, or Cleric spells with just Wizard, I'd strongly recommend picking one class instead of trying to do both Archivist and Wizard.

If you do decide to go with an Archivist / Wizard mix, you should look up early entry tricks for Mystic Theurge, and ask your DM which ones, if any, are allowed. I mean compare an Archivist 3 / Wizard 3 / Mystic Theurge 1 to either an Archivist 7 or a Wizard 7. You're getting 2nd-level spells when others are getting 4th-level spells.

If you're going to mix Rogue with another class, the Able Learner feat is great. With Able Learner, anything that's a class skill for one of your classes may as well be a class skill for all of your classes.

[Anthrowhale]

You might consider Factotum as well, since it fits the 'curious magic dabbler' reasonably well.

Otherwise, using Mystic Theurge does seem like a 'must' to have a viable character. Illumian[NaenKrau] Rogue 1/Wizard 1/Archivist 1/Mystic Theurge 10 with Able Learner at level 1 and Improved Sigil[Krau] at level 3 (for early entry) seems natural. You'll miss a full level of spells on both sides, but Krau means your caster level will not suffer and Naen means your top save DC will not suffer. With an Int focus, you'll end up with tons of skills and a reasonably effective spellcaster.

[ShurikVch]

Since you don't care about optimization, and both Archivist and Wizard use Int as their primary ability score, it may be useful to expand Int usage:

ACF:
Shadow Shaper (https://www.d20srd.org/srd/variant/classes/specialistWizardVariants.htm#shadowShaper) - Int to Hide checks at 5th level

PrC:
Bladesinger - 1-level dip for +1 AC (same thing as with Duelist and Invisible Blade, but with Bladesinger dip you wouldn't lose a level of casting progression; CL progression aside - Iaijutsu Master do it better)
Disciple of Baalzebul - 1-level dip for Int to Bluff checks (it's [vile] PrC!; check Mountebank and Rapscallion below!)
Iaijutsu Master - 1-level dip for Int to AC
Mountebank (Complete Scoundrel variant) - 1-level dip for Int to Bluff checks (but see Rapscallion below!)
Sanctified One (Complete Champion), Wee Jas - 1-level dip allow to add Int to your CL 1/day
Swiftblade (https://web.archive.org/web/20100327172812/http://www.wizards.com/default.asp?x=dnd/prc/20070327) - at 4th level you will get Int to Initiative, at 9th - an extra action while hasted

Feats:
Faerie Mysteries Initiate (Dragon #319) - extra hp
Insightful Reflexes (Complete Adventurer) - replace Dex for Ref saves
Keen Intellect (Dragon #318) - replaces Wis for Will saves, Heal, Sense Motive, Spot, and Survival checks
Knowledge Devotion (Complete Champion) - more damage with a successful Knowledge checks
Rapscallion (Dragon #315) - Int to Bluff checks

Spells:
Thunderlance (Sorcerer/Wizard 4; Spell Compendium) - adds Int to attack and damage rolls with the spell
Whirling Blade (Bard/Sorcerer/Wizard 2; Spell Compendium) - adds Int to attack and damage rolls with the spell

[RandomPeasant]

Beguiler is worth considering for this, I think. It'll get you some arcane magic and stealth skills, while still being an INT-based caster.

[liquidformat]

If you can figure out a way to pickup bardic knowledge and druidic language then Fochlucan Lyrist will progress both wizard and archivist casting. Spellthief might be a better choice for you rather than rogue.
Also checkout Loredelver, it is technically an illumian prc, which isn't horrible in and of itself but doesn't have being an illumian as a requirement though it is heavily implied throughout the PRC.

[Thurbane]

Not to completely nix your build idea, but, have you considered the Savant base class, from Dragon Compendium?

6 skill points a level (ALL skills as class skills), and it gets innate arcane (starting at level 5) and divine (starting at level 10) casting. Admittedly, the casting is pretty limited, but it's there. Also come with inbuilt trapfinding and sneak attack (slow progression).

I mean, it's generally considered inferior to Factotum, but it might fit what you are looking for in this character...

[Jervis]

Not to completely nix your build idea, but, have you considered the Savant base class, from Dragon Compendium?

6 skill points a level (ALL skills as class skills), and it gets innate arcane (starting at level 5) and divine (starting at level 10) casting. Admittedly, the casting is pretty limited, but it's there. Also come with inbuilt trapfinding and sneak attack (slow progression).

I mean, it's generally considered inferior to Factotum, but it might fit what you are looking for in this character...

Man I forgot how much of a mess savants were. They’re kind of a discount chameleon, in the same way that a boxer is a discount dentist.