The new base class from Dungeonscape has it all, and is so sexy it not only deserves, but DEMANDS a Handbook. It has the potential to multiclass into TONS of different PrCs and do nearly any and everything other classes can. The optimization opportunities are well-nigh endless, and as a labor of love (oh, the new-born passion of love at first sight!) I wish to undertake the creation of a Handbook for this most masterful of base classes.
To that end, this thread is a start. I bought Dungeonscape less than 4 hours ago, and haven't had the extended amount of time I'm going to need to do this class justice. However, I'd like to start this and reserve some posts to get going!
1st: Trapfinding, Cunning Insight, Cunning Knowledge. As a one-level dip this class is an exceptional boon. If you're human, changeling, or doppelganger, you can grab Able Learner to make ALL skills class skills for the rest of your career, regardless of what other classes you level up in. Cunning Insight lets you add your Int bonus to attack, damage, or saves as a free action at any time for an inspiration point, while Cunning Knowledge lets you add your Factotum level to any skill for one inspiration point. With only two points of inspiration this only goes so far, but it can still add up to a big boost if you're looking to make a scholar or Int-based Fighter. It also lets you customize the skill list of any other class you like, which can be a huge boon for meeting PrC requirements.
3rd: Cunning Defense, Brains Over Brawn. These two abilities are worth their weight in gold. Cunning Defense lets you add your Int to AC against one attacker per round for a point of inspiration - very handy. Brains Over Brawn, however, doesn't cost any inspiration - and it lets you add your Int bonus to Str and Dex checks and all Strength and Dex-based skills. This can turn any character with a decent Int score into a mobile skill monkey, which is a big boost! This is also the level at which you get a 1st level spell-like ability.
5th: Opportunistic Piety. Handy to be able to heal twice your factotum level + your Int mod Wis + 3 times per day. The turning is a bit less handy, but what the hell. You also gain a 2nd level spell-like ability at this level.
8th: Cunning Surge. This is the big one. If you could take an 8 level class that gave you one extra standard action in a turn once per encounter, would you? Of course you would! This is an especially important breakpoint for spellcasters, and works magic (literally!) with Chameleons, Ur-Priests, and other prestige-class spellcasters. This is one of the final breakpoints for this class; most will only take Factotum to 8th level or 11th level. Moreover, you get a 3rd level spell-like ability, which is handy for fueling Reserve feats. Though CustServ has made an official ruling that prevents the use of reserve feats, they do seem to be permitted by the origional text, and reasonable DMs will probably not see much of a problem with allowing them. More on this conundrum later.
11th: Cunning Breach. Another sexy spellcaster breakpoint. Spend 2 inspiration as a free action to automatically bypass a target's DR and SR for a round. This is especially handy on wand wielders and prestige casters.
13th: Cunning Dodge. This is sort of like the Rogue's Defensive Roll if Improved Evasion applied to it. Oh, and if you didn't have to make a save. In other words, spend 4 inspiration to totally avoid an attack that would lower you to 0 or fewer HP once per day. You also get a 5th level spell-like at this level.
16th: Improved Cunning Defense. This is less a breakpoint than the others (since it's so far into the class!), but it grants you Int to AC all day (but you can't wear medium or heavy armor - boo hoo). This can be nicely combined with Kung Fu Genius and a Monk's Belt for twice Int to AC - very handy.
18th: This is the level at which you get your highest spell-like ability - 7th level.
19th: Cunning Brilliance. This is the signature ability of a Factotum - the ability to imitate any Extroardinary class ability of any base class of up to 15th level for a minute three times per day. Wow.