Countermeasures against a Diplomancer

Question

A character with 40+ to social skillchecks is always a problem, moreso in a PvP campaign. True, Diplomacy is only so useful against PCs, but there are also Bluff and, especially, Intimidate. Those two have mechanical consequences even against other players and may pretty much make the battle one-sided.

The Diplomancer in our campaign was given even more power - the "roll to change someone's attitude" rule is on, and he casually makes NPCs fanatical, which allows him, among other things, to bypass the Leadership ban, effectively giving him an epic-level followership (dealing with the mooks is not really relevant to the question, through this info somewhat helps to understand the scale of his build). The problem is to NOT join his followers/run away screaming as he casually "Boo"s his opponents with something akin to unbuffed +30 to Intimidate.

So, I've been thinking - how can other players deal with the Diplomancer enemy WITHOUT calling upon the mighty Rule 0?

So far, I"ve came up with these solutions:

• Getting immunity to Mind-Affecting effects. Aquiring Mind Blank, or an Undead type are the most obvious ways to get it. Afaik, "Protection from X" effects don't work against mundane manipulations, but maybe there's something else to become outright immune to morale effects
• Not hearing the Diplomancer. Casting Silence on him, or Deafness on yourself will be sufficient enough in most situations (through there ARE ways around that)
• Nova him before he can utter a word. This option is too situational to depend on (Scry-and-Die is a good variant to it, but it's still not a perfect solution)

Are there any other ways to counter a Diplomancer?

Additional question: how can a wizard counter a Diplomancer? Dips (like into a Paladin) are a bad idea for him, so it's all about feats, spells and avoiding Arcane Spell Failure. The lower character/caster level required, the better. Cheap-yet-effective solutions are fine as well (defining "cheap" being under 16k gold, through the less, the better). Bonus points for solutions that don't hinder communication at least within the team.

Answer 1

Are there any other ways to counter a Diplomancer?

If you know you are fighting, you can prepare. You are facing somebody with epic diplomacy skills? Why not look for a defense in the real epic? In The Odyssey, the heroes are "attacked" by sirens. To avoid going mad, they seal their ears with wax. That's a 2 copper-piece defense against an epic skill monkey. It won't get any cheaper.

Apart from the obvious defense, why would a diplomancer even fight personally? The only answer I can come up with is that he was sent into an arena by a group of constructs that pit their slaves against each other. Because with such a high diplomacy value, he should be in the VIP part of the arena looking down on others fighting for him. That's the whole point of diplomacy skills, getting people to do stuff without fighting them.

D&D was never planned as a system to fight other players and the diplomacy system is considered broken by many. So as a last resort you could do what the computer games do that claim to be D&D: do not allow skills in combat.

Answer 2

I assume we are talking about direct combat as there is pvp tag. I also assume your group sticks with RAW about Diplomacy so it can't affect a PC in any way.

Measures against Bluff and Intimidate differs slightly (your third solution of course will negate both problems).
Hearing also isn't directly listed as a requisite for both Bluff and Intimidate. Well, their combat applications at least. Feinting for example is about pretending to pierce one of your opponent's body parts with a pointy thing but actually aiming at another. It have nothing to do with speaking in general.

Immunity to Mind-Affecting (as well as immunity to Fear effects) is nice, but it won't counter Bluff (you need to be mindless instead). Still it will take care of Intimidate.
In addition to the staff you listed you may try to find some interesting forms to Polimorph into. As that spell changes your type, it'll give you all (arguably) benefits listed for types directly. Plant's immunity to Mind-Affecting is a no-brainer while Mindless trait of Vermin and Oozy types is subject to arguments. All people playing D&D whom I'm familiar with won't allow you to have it and Int score simultaneously.
There also is a list of useful magic items. There may be more of course, this is just to begin with. Unfortunately items (other than +X competence bonus to Sense Motive) also won't help against Bluff.

Also, as Sandwich has pointed, you don't realy have to blast your enemy to death. Blindness/Deafness is well enough if he can't make that save. There are tonns of effects like that.

It is other story that if you are a wizard, best you can do is just not to get into his reach. Note that combat applications of either skill require user to threaten his opponent. There are exeptoins, may be even that I don't know of, but generaly they are close combat things (that thing causing covering condition certainly is).

Edited (Diplomacy)
So now when that "influence PCs" rule is on we are faced with completely different issue. First and foremost problem here isn't realy covered in your question. Diplomacy, even that epic, is not a sort of mind control or misleading. It is not something bad, generally. It is performed through reason, persuasion and a bit of personal credibility. So my question now is, why your character would even want to seal his ears / cast that silence? He is not expecting the attack - it is just not an attack. In or out of combat - it doesn't matter. He just talks. He is not necessarily cheating on you, or is trying to use you.
From that point a decision to try not to listen to him made in advance can be treated as some sort of metagame and, depending on the DM, may be viewed as not quite fair play. This is kind of opinion based, but it is how I see the whole thing.

What i suggest to make things better for your character is to suggest to diplomancer's player and DM that the player must roleplay what that character is saying.
What could he say to that band of orcs, charging on him (or his group), to make them stop hearing just a few sentences? How he convinces your character to join him? He of cource not required to convey emotions or persuasiveness of his character's speech. But at least general idea of his negotiation efforts. Is he offering something to those orcs? Is he using their ignorance and implicit faith calling to them with the names of their gods? Attempt just should be reasonable, or else DM may penalize his check or simply ignore it. It is the other matter, will he accept it or not.
Also bear in head that you're still only helpful even if it is +150 on the check. You still remember who your allies are and what goals you're aiming at. You're not like slave no matter what!
Your other option is to stick with nvoigt's answer (in which case you probably should accept his).

Returning to the above.
Immunity to Mind-Affecting does nothing against Diplomacy (as with Bluff). Given houserule is also limits the list of Save-or-Suck effects, but there is still plethora of sufficient ones.