8v1 PC fight, help preparing (3.5)

[flappeercraft]

So right now a group of friends of my dad (yes they play D&D, actually it was my dad who brought me into D&D tbh) just finished the Savage Tide storyline and successfully killed Demogorgon but they felt unfulfilled as they thought that it was hard but did not meet their expectations. Due to that since I was not part of this one campaign the DM (My dad) and I are preparing something as a last adventure, it is going to be instead of DM vs PC, a 8 PC's vs 1 PC. I have a Wizard Fire orber build that should be able to take them out without too much trouble but the problem is that it is 8 characters level 21-24 against one 21 level character who has 4 of semi optimized bodyguards, 3 being level 16 and 1 level 20 and a beholder. The problem here is not that I don't have enough raw power to take them out but there 8 players who are a part of this which means that they will get way less flaws in their plans as 8 people revising them vs 1 doing so is way better and also they have been playing the game more than I have lived as they have played over 28 years. So due to that I was allowed to make a stronghold and to optimize which I have done to a decent extent just between the point of breaking the game and not doing so. I need to prepare against multiple things due to this so I will probably need some help of the playground to prepare. All cheese is allowed, traps are allowed, 3.0 things that were not updated are allowed, custom magic items are allowed and pretty much everything is allowed. Only things not allowed are ToB for some reason, weapons of legacy and being psionic but all psionic items even custom are allowed. In case this is useful for you we are in greyhawk but spells, feats and classes from Faerun and Eberron are allowed as we just rule them as a separate plane and we can just plane shift there and learn.

[Schattenbach]

Do you actually want/are allowed to to change your character build?

Anyway ... limited wish based psychic reformation to change the build somewhat up should be allowed in pretty much any case? How are things in regard to epic spellcasting?

Details about both sides class composition might be worthwhile?

How much wealth do you actually have to work with?

[flappeercraft]

Do you actually want/are allowed to to change your character build?

Anyway ... limited wish based psychic reformation to change the build somewhat up should be allowed in pretty much any case? How are things in regard to epic spellcasting?

Details about both sides class composition might be worthwhile?

How much wealth do you actually have to work with?

I have already used psychich reformation, a lot, there is no epic spellcasting just because we think it is too abusive, it is not banned but we just rather not use it but metamagicked pre epic spellcasting we do use. For gear on my build I have 975,000 GP of which all is used and my build is a Fighter 1/Domain wizard 5 (abj)/Homebrew PrC 10/Abjurant Champion 5. If you want to check out the PrC it is Spell Combatant and you can find it on this doc https://docs.google.com/document/d/1aH8qcAJC55s2VbxhGTkr-Gtw2X4O14mOQw16aCp0dOI/edit?usp=sharing On shenanigans used there is a bit of thought bottle use and Fusion + Astral seed involved but you can check out the build here https://drive.google.com/file/d/0B5mKst8azowjQXV4bUtXRzJoRXM/view?usp=sharing

On their side IIRC a wizard with a couple PrC's although I don't remember which, a favored soul, a paladin, a champion of corellon, a dread necromancer a duskblade and a ranged focused archer. I don't have too much information on them just that they are all 20-24 level.

[Name1]

I'd say you should have your main guy be a Red Mage Wyrm Wizard to get access to a high-CL Blasphemy. I say Wyrm Wizard over taking Arcane Disciple because you can devote yourself to an Elder Evil that way (delicious bonus feats) and can have your bodyguards be Ur-Priests, which is great because it means level 9 spells and DMM for your Level 16 guys. That also gives you more feats you can use to buff up your [Fire]power. If you don't want to be a Red Mage, you can be a Recaster instead and use the abilties from that PrC to apply metamagic without changing the slot.

I'd suggest one level 16 to be a Factotum 8/Urpriest 8 to pull off Surge of Fortune + Vorpal in one round.
For the level 20 guy I'd say Shaedling Savage Bard 1/Urpriest 4/Entropomancer 10, because Shaedlings can create any item they want at will and a Sphere of Annihilation is literally no-save death. Combine that with a Rod of Excellent Magic + the ability to cast Gate to get a Solar into melee and the Tomb Tainted Soul feat in combination with the Ruby Rod of Asmodeus and you have yourself a powerful guy in the back.

EDIT: Since you already have your main guy... I guess you can have the Red Mage be a bodyguard.

[flappeercraft]

I'd say you should have your main guy be a Red Mage Wyrm Wizard to get access to a high-CL Blasphemy. I say Wyrm Wizard over taking Arcane Disciple because you can devote yourself to an Elder Evil that way (delicious bonus feats) and can have your bodyguards be Ur-Priests, which is great because it means level 9 spells and DMM for your Level 16 guys. That also gives you more feats you can use to buff up your [Fire]power. If you don't want to be a Red Mage, you can be a Recaster instead and use the abilties from that PrC to apply metamagic without changing the slot.

I'd suggest one level 16 to be a Factotum 8/Urpriest 8 to pull off Surge of Fortune + Vorpal in one round.
For the level 20 guy I'd say Shaedling Savage Bard 1/Urpriest 4/Entropomancer 10, because Shaedlings can create any item they want at will and a Sphere of Annihilation is literally no-save death. Combine that with a Rod of Excellent Magic + the ability to cast Gate to get a Solar into melee and the Tomb Tainted Soul feat in combination with the Ruby Rod of Asmodeus and you have yourself a powerful guy in the back.

EDIT: Since you already have your main guy... I guess you can have the Red Mage be a bodyguard.

Problem is that the guy i'm controlling is supposed to be really devote to Hextor, he is part of an empire from where he got the stuff for the Spell Combatant PrC and that empire you MUST follow Hextor, this also can take away the use of an Urpriest as he is supposed to be like as devote as you can get and I don't think that someone like that would literally steal the magic from his god. Also the reason that I also need Hextor anyways for this is that due to the arcane disciple feat with the domination domain I get the monstrous thrall spell in my spell list which is what he uses to control the bodyguards. The rest I might implement and I will try adapt the things I can't do to something similar I can.

[Schattenbach]

Using some epic warding spells (or hiring some epic NPC spellcaster to do that for you) might still be worthwhile, though.

You could try to use some minor wealth tricks (like those using Wall of Salt) if you're running low on funds for your fortress.

Some general suggestions ... if you can still change their classes, Dweomerkeeper might be useful for one of your underlings (well ... more like supernatural spell, but that's plenty enough already ... as you can use it do solve both money - and exp cost issues - & create sufficiently powerful wardings), as is Incanatrix (the later one might also fut well together with your character as well), otherwise ... use some of your Wealth to hire one for you.

One particulary mean trick you could use against that demon lord slaying group of players is any kind of trap involving Jovocs ... they're (unprogressed) only CR5 critters with 4 HD but can attempt to summon another one once per day that can be trapped somewhere even if you cannot be bothered with actually controling them (their physical strength is too weak to damage anything that is relevant, anyway). Their Aura of Retribution makes it so that whenever they take damage of from any source, any Nontanar’ri within 30 feet takes bascially unavoidable damage equal to half whatever damage they took (or rather 1/4 as they're obviously going to make that fortiude save for half damage) ...

[Name1]

Problem is that the guy i'm controlling is supposed to be really devote to Hextor, he is part of an empire from where he got the stuff for the Spell Combatant PrC and that empire you MUST follow Hextor, this also can take away the use of an Urpriest as he is supposed to be like as devote as you can get and I don't think that someone like that would literally steal the magic from his god. Also the reason that I also need Hextor anyways for this is that due to the arcane disciple feat with the domination domain I get the monstrous thrall spell in my spell list which is what he uses to control the bodyguards. The rest I might implement and I will try adapt the things I can't do to something similar I can.

You could cheese your way through the requirements for Entropomancer via Versatile Spellcaster and Earth Spell. This doesn't give you 9th level spells, but you can always just create a scroll of Gate instead.

The Factotum can work via Recaster and Sublime Chord, using similar cheese and choosing Surge of Fortune as one of the two learned bonus spells.