I have an Asmodean Advocate. Barrister. Devil-Worshipping-lawyer. +18 to Bluff at 3rd level.
Mummer's Ruff and Clockwork Bug.
Put on the Mummer's Ruff and there is a +10 bonus to Bluff while imitating someone's voice, that is effectively +28 for my guy.
Clockwork Bug records conversations for one hour once set. It is already a useful tool for a lawyer-type to have for recording, "legally unassailable," witness statements and suspect confessions, but add in the +28 potential for creating false confessions and statements...
Except your definitely going to have people who say that the recording was magically created (and they're right).
So you're going to need other proof. Remember, this is a world of magic and people are aware of it. They don't just accept something at face value.
Also, it seems like the +10 bonus from the mummer's ruff only applies to pretend to be a specific person, not to make a generic lie more believable.
For the area in Golarion my PC is in, relatively isolated, no courts and my intended use to provoking intrigue this actually is viable.
Not seeing ANYTHING there that prevents the use as I mentioned, and I do intend to use it to imitate a specific person (the curate of a rival faith.)
I didn't say anything prevents the use, what I'm saying is the bonus to your bluff is only for the purpose of sounding like a different individual. For instance you couldn't just use the mummer's ruff to enhance all lies by 10, it only enhances your bluff to pretend to be someone else.
If you mean there may be two Sense Motive checks, one to believe the voice belongs to the Curate (+28 Bluff) and another to believe the lies (+18 Bluff) I can see how at first you may think the DM would go that way, BUT... if the first check is a success, why would there be a second? Think that over for a second. They believe it IS his voice.
His voice (as far as they are concerned) is claiming to be responsible for murders in his past, betraying his faith, that he will frame our party for all manner of bad deeds and everyone will believe him, that we can do nothing to stop him, and eventually he will cast down the Castellan or have him bow before him, etc. Would they then ask him, "Why are you lying?"
The end game is not necessarily to get the victim arrested and hanged (though that would be nice!), but to subvert his standing and moral authority, to have the locals begin to doubt their local leaders.
This would come on the heels of a different, unrelated plan to get the Captain of the Guard arrested for corruption.
Our party will be taking over, and we need to undermine the local authorities first, get the sparse population to lose confidence in the local leadership.
Even if they believe it is that person's voice, they can still believe that person is lying or that they were coerced/dominated into making that statement.
True dat.
But there are ways to manipulate the, "big reveal," to have the highest probability that the Curate denies saying it at all. Which would undermine any claim later that it was due to being dominated/coerced.
Ask or accuse of the statements first, when he denies, get more strident, more forceful. Cause him to lose it a bit and make him be ABSOLUTE in his denial of ever saying anything of the sort.
Then the big reveal.
Claiming to be dominated or coerced after that would be problematic.