3.5 Disguise check for a warforged posing as human.

[Rukia]

I'm running a campaign in FR and I've introduced a small number of warforged into the world. They aren't from Eberron per say, but instead created by the Gnomes in Lantan. Basically they were an experiment and once they realized they were sentient they stopped due to their own moral issues with the unintended outcome. With so little of their kind in the world it seems plausible that they'd want to keep their identity somewhat hidden to keep from garnering too much attention from those that don't know of their existence.

That being said I want to introduce an NPC to my players that is a warforged but in disguise as a human. He would be relying solely on a hat of disguise and a disguise kit to pull it off as his class doesn't have the skill(it's an untrained check as best as I can tell). I'm trying to figure out the rules of disguise to see how plausible it is.

Basically it says you can take 10 or 20 on creating a disguise. Hat of disguise adds +10 and a disguise kit adds +2. Meaning I could feasibly pull off a 32 minus any negatives for the change of race. Since it will be a generic human, none of the PC's will know the person so there won't be any bonus modifiers as if he was attempting to be someone they knew.

Question is how often would they theoretically get a spot check versus the disguise? Apparently you treat anyone coming into contact with the person as if they were taking 10 so long as they aren't suspicious. This NPC will be friendly and not an enemy so once he gains their trust and they haven't spotted him I'd like to assume that the chances of any of them seeing through it without extenuating circumstances probably wouldn't have a clue.

One more thing is the hat of disguise apparently only lasts 10 minutes, though it can be reapplied before it wears off indefinitely. I don't want to have to reroll a check every 10 mins, nor do I want to deal with constant take 10's with PC characters. At some point it will probably be revealed to them, I just don't want to "DM fiat" that it "just works" and would at least like to have some semblance of RAW. Perhaps give them all one check per day they are with him, and perhaps every day they don't spot it and gain more trust they accrue a negative on the check?

If one of them ever had to touch him, carry him, etc.. then I'd assume they'd realize something was up due to the weight and tactile features of the warforged versus a human. If they touched him on a part of his body that was armored(ie; torso) then they probably wouldn't notice, but an arm/face/leg]etc... might give it away. Perhaps I'm over-thinking this, but I just wanted some input to see if I was on the right track.

[Parra]

Question is how often would they theoretically get a spot check versus the disguise?

The first time they meet the Warforged after the Disguise is refreshed.
Then anytime they are given reason to doubt the disguise i.e. being observed changing outfits

[Vaz]

It's only a -2 to change race, but it is opposed by the enemy Spot check.

Now, spot is Wisdom based, and most people you need to slip past are often Wis10-12 at best, with perhaps 4-6 ranks in Spot, so you're looking at (average) 6-25 to beat. If you can beat that, you'll be fine. (I know it's an NPC, but it's a benchmark; there's no point in running a Disguise character that can't avoid enemy scouts.

Hat, Cha Bonus, Bluff Synergy, Disguise Kit = +14, take 20 for +34. You can easily beat enemy Scouts.

Of course, that's provided they're not magical, and don't have True Seeing to beat the Hat of Disguise or Alter Self.

As for the PC's not seeing him for what he is, I hope you've banned true seeing; just one Invisible enemy or silent image blocking the path would result in a nasty surprise for the party.