Making a character no one knows is a caster - Some help needed

[Prime32]

If you go the above route, learn Drow Sign Language. It explicitly boosts the DC to identify your spells whether they have somatic components or not, and if nobody can identify your spells, they don't necessarily know they're spells. The Conceal Spellcasting skill trick may also come in handy (already been suggested, I just thought I'd mention it again). That way you can save a few metamagic expenses each day.

Eh, does Drow Sign Language come with rules on using it in spellcasting? Because otherwise I'm not sure how that would work.

[Jackinthegreen]

If you go the above route, learn Drow Sign Language. It explicitly boosts the DC to identify your spells whether they have somatic components or not, and if nobody can identify your spells, they don't necessarily know they're spells. The Conceal Spellcasting skill trick may also come in handy (already been suggested, I just thought I'd mention it again). That way you can save a few metamagic expenses each day.

Eh, does Drow Sign Language come with rules on using it in spellcasting? Because otherwise I'm not sure how that would work.

Drow of the Underdark page 46 says:

Spellcasting: Drow Sign Language cannot be used as part
of a spell’s verbal component.
However, as pointed out in Chapter 1, Drow Sign Language
is quite similar to the somatic gestures used to cast
arcane spells. An arcane spellcaster who is fl uent in Drow
Sign Language gains a +2 bonus on Spellcraft checks made to
identify a spell being cast (if it has a somatic component), and
increases by 2 the Spellcraft DC to identify any of her spells
as she casts them (whether or not those spells have somatic
components).

[Bauglir]

If you go the above route, learn Drow Sign Language. It explicitly boosts the DC to identify your spells whether they have somatic components or not, and if nobody can identify your spells, they don't necessarily know they're spells. The Conceal Spellcasting skill trick may also come in handy (already been suggested, I just thought I'd mention it again). That way you can save a few metamagic expenses each day.

Eh, does Drow Sign Language come with rules on using it in spellcasting? Because otherwise I'm not sure how that would work.

It's mostly just to make it ever so slightly harder for people to Spellcraft their way to knowing you're casting a spell, so that you can bluff your way through by claiming to just be drunk and flailing about and you'd appreciate it if people would lighten up it's not like you're hurting anything.

[Wiggins]

This is shaping up to be really really fun. Thanks guys!

Anyone care to throw in any competing build examples?
I'm not good at modifying an idea once I have it down on paper unless I have something to bend it towards.

[Wiggins]

Okay, I'm so torn I'm going to build it twice.

1. Pretending to be a Fighter Rogue, rushing first into Unseen Seer then into Havoc Mage, going sorcerer to play merry with the action economy once I hit arcane spellsurge

2. As one half of a Gestalt Build, pretending to be a Rogue/Ranger/Scout/Marshall, when in fact I'm all those things down one side, and this up the other.
For this gestalt version I'll probably go the Sleight of Hand Optimisation route (as I can actually get it as a class skill), and see if I can blag a +2 bonus from Drow Sign Language (Marshall has languages as a class skill).

[Wiggins]

The Gestalt version.

A Ranger/Rogue/Marshall/Swordsage just happens to suit small characters like, say, gnomes to a tea.

What the hell, lets get some Shadowcraft up in here.

And no one expects Divine Shadow Evocation, let's make him a secret Cleric. Preparing 1 or 2 Cure Light Wounds per day at level 10 should convince them I'm Ranger all down one side.

[Wiggins]

Doh! Arcane Thesis requires Arcane casting
[FAIL]
I need to not try to build late at night