Quick question on a factotum ability

[King Atticus]

My question is on cunning strike. I'm trying to find out if it's legit (by means other than DM handwave) for me to spend more than 1 Inspiration Point and up the sneak attack dice. By the way it's written to me it looks like I'm stuck to +1D6, am I reading it too strictly or is that it; 1 point for 1 die.

All thoughts are welcome and appreciated.

[Salanmander]

My question is on cunning strike. I'm trying to find out if it's legit (by means other than DM handwave) for me to spend more than 1 Inspiration Point and up the sneak attack dice. By the way it's written to me it looks like I'm stuck to +1D6, am I reading it too strictly or is that it; 1 point for 1 die.

All thoughts are welcome and appreciated.

I'm AFB at the moment, so I may be wrong, but I think the way that works is this:

It doesn't take an action, and provides an untyped bonus, so it stacks with itself. Therefore you can use it multiple times and they stack.

The reason you can't do that with the other abilities is that they provide a typed bonus, and so wouldn't stack. (This is the part I'm least sure about, I forget if the other bonuses are typed or not.)

[Khedrac]

It doesn't take an action, and provides an untyped bonus, so it stacks with itself. Therefore you can use it multiple times and they stack.
Actually I think you will find that while Untyped bonuses stack, bonuses from the same source never stack with themselves (unless explicitly stated that they do) so this logic is flawed.
I am also afb so cannot look at the original question properly - sorry.

[Jarian]

You're correct. By default rules, you can only get +1d6 sneak attack. I would recommend working with your DM to determine a logical progression between Rogue and Spellthief that you both find fair however, since an average of 3.5 bonus damage is pretty pitiful.

[Curmudgeon]

I'll start with a couple of rules citations for you.
Stacking

In most cases, modifiers to a given check or roll stack (combine for a cumulative effect) if they come from different sources and have different types (or no type at all), but do not stack if they have the same type or come from the same source (such as the same spell cast twice in succession). If the modifiers to a particular roll do not stack, only the best bonus and worst penalty applies.
Sneak Attack

This is exactly like the rogue ability of the same name. The extra damage dealt increases by +1d6 every other level (1st, 3rd, 5th, 7th, and 9th). If an assassin gets a sneak attack bonus from another source (such as rogue levels) the bonuses on damage stack. The normal case is that a bonus to your damage roll from the same source (Cunning Strike, Sneak Attack, or whatever) won't stack with itself. If you're allowed to spend 3 IPs on Cunning Strike you'd get 1d6/1d6/1d6 sneak attack: roll 3 d6s, and take the best of them. If Cunning Strike had stacking language such as in the Assassin's Sneak Attack class feature you would be allowed to add them instead.

Of course, whether you're allowed to spend more than 1 IP is up to your DM, because Cunning Strike is consistent in its use of the singular.

[prufock]

I have two questions related to the factotum (Du 14) and sneak attack:
1. Can a factotum spend more than one inspiration point on cunning strike to gain more than 1d6 points of sneak attack damage?
2. Can a factotum of 19th level use cunning brilliance to emulate a rogue’s sneak attack ability?

Answering your questions in order:
1. Yes, you can use multiple inspiration points to gain additional sneak attack damage.
2. It’s reasonable to assume that sneak attack is an extraordinary ability. When in doubt, the DM should decide if an unmarked ability qualifies. Anything that lacks a clear, supernatural element should be fair play.

While much maligned, the FAQ is at least a semi-official answer.

[Curmudgeon]

While much maligned, the FAQ is at least a semi-official answer.
The reason the FAQ is much-maligned is that, among other things, these answers are both demonstrably incorrect. I've already quoted the stacking rule showing why the first answer is wrong. The second answer's "reasonable to assume" idea is also bogus. From page 180 of Player's Handbook:
Natural abilities are those not otherwise designated as extraordinary, supernatural, or spell-like. And from page 118 of Rules Compendium (which came out half a year after Dungeonscape and the Factotum class):
Natural abilities are those not otherwise designated as extraordinary, supernatural, or spell-like. They’re rarely identified as natural—that’s assumed—and they rarely take a distinct action to use.

[Psyren]

FAQ says yes, (http://www.wizards.com/default.asp?x=dnd/ask/20070412a) so show that to your DM and you're good.

That's all I'll say on this to avoid yet another drag-out forum battle.

[prufock]

The reason the FAQ is much-maligned is that, among other things, these answers are both demonstrably incorrect.

I agree with your analysis by RAW, but the OP seemed to be looking for some official support on stacking the sneak attack damage. The FAQ is the closest there is.

[King Atticus]

Thanks for the answers everyone. The FAQ suits my needs just fine and is the answer I'll go with. I appreciate the responses.