Epic Diplomacy

[ByzantiumBhuka]

Epic uses of skills in 3.5 can lead to ridiculously high DCs. The highest I can find is in Diplomacy/Performance, where a result of 150 or more can turn someone from hostile to a fanatic in your favor.

Is this even possible?

That is to say (given any number of magic items or spells), can a single character have a result of 150 on a Diplomacy or Performance check, either a single time or consistently?

[Doctor Despair]

Yes. It is possible to get infinite checks, but even setting that aside, it is possible to get very high charisma bonuses. Marshal effectively doubles it, too

[sleepyphoenixx]

Easily. Diplomacy is one of the easier skills to optimize, and getting a consistent 150 is possible quite a bit before level 20 if you focus on it to the exclusion of everything else.
Try a search for "Diplomancer", it's a pretty famous TO build.

[Anthrowhale]

At level 20, you can easily achieve 139=23 (ranks)+23(Item Familiar)+20(Competence, Guidance of the Avatar)+15(Insight, Divine Insight)+10(Luck, Improvisation)+20(Surge of Fortune)+14(Charisma)+14(Circumstance, Marshal). Scraping up another +11 is likely very doable.

[AvatarVecna]

Magic-Blooded Unseelie Fey Lesser Aasimar
Marshal 20

Charisma 43 (+16):
Base 18
Race 6
Age 3
Tome 5
HD 5
Enhancement Item 6


Skills:
Bluff 23
Concentration 1
Diplomacy 23
Knowledge (Nobility & Royalty) 23
Sense Motive 23


Traits:
Honest
Polite

Feats:
HD 1: Cool Head
Marshal 1: Skill Focus (Diplomacy)
Flaw: Great Diplomat
Flaw: Courteous Mageocracy
HD 3: Item Familiar
HD 6: Blade Meditation (White Raven)
HD 9: Negotiator
HD 12: Sacred Vow
HD 15: Vow Of Nonviolence
HD 18: Vow Of Peace


Diplomacy +138:
Ranks 23
Charisma 16
Marshal Minor Aura 16
Traits 2
Feats 43
Synergy 6
Competence Item 30
Circumstance Item 2


This build gets +138 just walking around all day, albeit for admittedly quite a lot of investment. I'm sure there's more than a few spells (probably previously mentioned in this thread) that could temporarily boost it even higher. Naturally, this gets a touch easier in epic:

Lesser Aasimar
Marshal 24

Charisma 32 (+11):
Base 18
Race 2
HD 6
Enhancement Item 6


Skills:
Bluff 27
Diplomacy 27
Knowledge (Nobility & Royalty) 27
Sense Motive 27


Traits:
Honest
Polite

Important Feats:
HD 1: Cool Head
Marshal 1: Skill Focus (Diplomacy)
HD 3: Item Familiar
HD 21: Epic Skill Focus (Diplomacy)
HD 24: Epic Reputation


Diplomacy +148:
Ranks 27
Charisma 11
Marshal Minor Aura 11
Traits 2
Feats 53
Synergy 12
Competence Item 30
Circumstance Item 2


That build has +148 just walking around all day, and doesn't even have most of their build dedicated to it even. Diplomancy is just one of the things they're good at. Of course, your initial post didn't even say "can this be done without being epic", which it most definitely can, but also...you realize epic just goes on forever, right?

Lesser Aasimar Bard 42

Charisma 36 (+13):
Base 18
Race 2
HD 10
Enhancement Item 6


Skills:
Bluff 45
Diplomacy 45
Knowledge (Nobility & Royalty) 45
Sense Motive 45


Important Feats:
HD 3: Item Familiar

Diplomacy +153:
Ranks 45
Charisma 13
Feats 45
Synergy 18
Competence Item 30
Circumstance Item 2


+153 with just Item familiar, a +30 item, and synergy bonuses. Get far enough, and you don't even need item familiar:

Human
Bard 100

Charisma 40 (+15):
Base 15
HD 25


Skills:
Bluff 103
Diplomacy 103
Knowledge (Nobility & Royalty) 103
Sense Motive 103


Diplomacy +148:
Ranks 103
Charisma 15
Synergy 30


+148, no feats, no spells, no items.

[Biggus]

Epic uses of skills in 3.5 can lead to ridiculously high DCs. The highest I can find is in Diplomacy/Performance, where a result of 150 or more can turn someone from hostile to a fanatic in your favor.

Is this even possible?

That is to say (given any number of magic items or spells), can a single character have a result of 150 on a Diplomacy or Performance check, either a single time or consistently?

Do you mean "is it possible by level 20"?

[Vaern]

There's higher skill DCs than that. Epic spellcasting requires a spellcraft check in order to cast the spell, which can be arbitrarily high depending on how powerful you make the spell. One of the sample epic spells (Vengful Gaze of God) requires a successful spellcraft check with a DC of 419 to cast.

[Gruftzwerg]

There are plenty of more or less cheesy ways to pass any skillroll DC.
Most obvious are infinite loops ala pun-pun, BoBaFeat..

But there are much more mundane options to achieve this like:

Aid Another (https://www.d20srd.org/srd/skills/usingSkills.htm):

You can help another character achieve success on his or her skill check by making the same kind of skill check in a cooperative effort. If you roll a 10 or higher on your check, the character you are helping gets a +2 bonus to his or her check, as per the rule for favorable conditions. (You can’t take 10 on a skill check to aid another.) In many cases, a character’s help won’t be beneficial, or only a limited number of characters can help at once.

In cases where the skill restricts who can achieve certain results you can’t aid another to grant a bonus to a task that your character couldn’t achieve alone.

See also: Aid Another in Combat
Sure aid another has limitations. But when it comes to Diplomacy, I see it plausibly to don't set a limit. I mean isn't that how Diplomacy works? So, once you have achieved a certain number of fanatics, everybody will give in to your speeches ^^