Quote Originally Posted by Psyren View Post
No, I said no such thing. You're treating the kit like it is its own ability but that's now how either version of the game works. There are only 6 ability checks in D&D, corresponding to the 6 ability scores - Str, Dex, Con, Int, Wis, and Cha. I'm not making a "Disguise Kit" check - I'm making a Charisma check and then asking the GM whether a proficiency or expertise my character has applies.
If you make a Disguise, you have to make an ability check. If you have proficiency in the Disguise Kit, you can add your proficiency to the ability check. The Deception skill does not let you add your proficiency bonus to a check when you make a disguise. I don't know where you are getting that from.
If I'm trying to fool someone with a false identity and I have Expertise in Deception and Proficiency in a Disguise Kit, then I can ask the DM if the Disguise I created with my use the Disguise Kit to grant advantage on my Charisma (Deception) roll, resulting in Expertise + Advantage as per Xanathar's 78 / UA8 pg 30.
No one is disputing this (assuming people are using this optional rule, as an example two of my DMs do not use this). It's just irrelevant. The assassin can also do this if there is some obvious reason to suspect him and he needs to make a Deception check. The point is the actual disguise itself and the false identity. You haven't demonstrated how you can even come close to an unfailing false identity. Looks like you're getting around 16 or 17 on average on your check, and same for your forged documents. Anyone that challenges you can beat that with just a lucky die roll, let alone any modifiers the DM might add.
Adding to the above, the challenge here is having a believable false identity. Both Disguise and Forgery kits will play a role in that, but the ultimate check would be Charisma (Deception), to be believed. Simply putting on a wig without any attempt to act like the persona would act does nothing.
You need a believable disguise first Psyren. Otherwise the uber Deception check that you're making will be to explain why you are wearing a wig and a false nose, and why you have falsified papers. That's not a check you want to be making. In fact, as I already said, anyone noticing your crappy disguise/papers might not believe any lie you tell them, might immediately try to remove you from the premises, detain you, get their supervisor, etc. Like... you're trying to bypass the entire disguise part of the false identity by just assuming that you can lie yourself into convincing someone you have a credible disguise. That's now how it works. You have to have a credible disguise, and then lie to play the part convincingly.

The level 9 Assassin doesn't have to do that; they are simply assumed to be the false identity they are presenting.
If my base class gives me a minimum roll of 20, very likely approaching 30, then I don't actually need a crappy ribbon that guarantees believability - I'll take my chances. (And a subclass with actual features.)
This only works because you are completely bypassing the need to roll for Disguise/Forgery. You're just subsuming it into the Disguise skill, as I jested in my previous post about you DMing for someone that wants to replicate the feature.

In reality, you would need to roll to forge those documents and make those disguises, without Expertise, and with your cha/int modifier. So yes, you will take your chances and not have anywhere near the success rate of the Assassin. You'll be straining your DMs generosity by having to roll Deception to explain that you were caught in a storm and your documents got wet and you had to dry them out and that's why they look funny and explaining that the reason your uniform looks different is because it was a hand me down when resources were tight, etc. Like... instead of actually making progress and infiltrating this place, you're going to be using your psi-dice to keep the mission from failing in the first interaction, assuming your DM even lets you salvage a botched forgery/disguise contest.
Yes - if there's only a week before the infiltration and Assassins are the only ones who can actually attempt to infiltrate in that week, regardless of training, then you are functionally telling Bards and Soulknives and everyone else to go take a hike.
You're conflating a simple infiltration (breaking and entering) with assuming a persona that is so well-supported people don't question its authenticity. The two are not the same thing.

Quote Originally Posted by Skrum
But in practice, I just don't see it working that way. For instance, if I was the DM and I was running a campaign that took place within high fantasy Gotham City and the entire game was about corrupt political organizations jockeying for power with violent crime syndicates, and the players were presented with the problem of collecting info from someone and they wanted to run an elaborate, weeks long heist involving disguises....like where would Infiltration Expertise fit in? If one of the players had the ability, would I say "perfect, not even going to make you roll, here's the info." Very plausible answer. What would I say if no one had the ability, but they wanted to do a heist anyway? In what two ways should I resolve it such that 1) Infiltration Expertise actually means something, and 2) while still encouraging creativity from the players (like what if one of them is playing a changeling eloquence bard?? Do I call for checks in excess of 23, just so they don't auto-pass? What if no one is playing a super-spy, and it's just the warlock riffing with Mask of Many Faces and a +9 Deception check?).
I don't understand the dilemma here. Why can't the warlock with +9 Deception and Mask of Many Faces dupe someone into giving them information? It's just a different way to do it. I'm not sure what's the confusion here. The warlock is not creating a whole new persona that is affiliated somehow with this organization and can waltz in. The warlock is likely using Mask of Many Faces to make themselves look like someone else in the organization, and then their Deception is to pose as that person. People that interact with the illusion will figure it out, and the warlock will need to make checks to keep the ruse going so long as they haven't discovered the illusion.

An assassin is going to do exactly what Batman does in this exact same scenario in actual Gotham City; assume the guise of someone in that circle and gather information that way. Batman uses the identity of Matches Malone. It's a little different, as Malone was a real criminal already that died, and no one knew except Batman, so he takes the identity and uses it to infiltrate the criminal underworld whenever he wants. The assassin would do the same thing, except they have to invent up a new persona, but they also get the background to make it like a real life person that people believe exists.