[3.5] Help with a "Besieged/Infiltrated City"

Hi

Short Background:

A Death Slaad and his companions, a Succubus and an Orc Leader entered and nearly conquered the City. (some sort of conquering it from the inside) They made the chief of the town guard and the royal guard their slaves. The city is surrounded by some sort of chaotic Genesis spells.
No one can leave the city, with some hidden exceptions, everybody can enter but maybe will mutate because of the chaotic component of the spell.
Big number of townsfolk mutated and is now controlled by the evil forces.

There are still normal guards and townpeople who defend parts of the city, maybe a bridge or some passages and buildings. They hope for the Players to arrive and rescue them. The Adventureres meanwhile are undertaking a different adventure in a dungeon, so they don´t know something about the attack.

The Evil Forces are aggressive and don´t wait until the heroes reach them.
They know there is an adventuring party around somewhere, not knowin that they are somewhere else right now.

Team Evil consists of: The Orcs from the north (+ a leader) the Death Slaad and some of his followers, wich are the strognest enemys, and the Succubus. maybe with some minions.

The situation when the PCs enter the city: The city is quite destroyed, and the attack of the evil forces started some days ago.

The town I take is in the Valley of Obelisks (Shattered Gate of Slaughtergarde Campaign Setting). It should be Sumberton i think (capital city of the Valley, and the PCs know it quite good)
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No my questions:
1. Is there any trouble the PCs could bring me as a DM ?

2. Any ideas how i can tell the PCs that the Evil Forces are the ones who take the initiative (At least they aren´t defensive like many evil Villains in other adventurers)
I thought of that: The Pcs wittness a battle between evil forces and the "rebels" where one of the evil leader speaks to them. something like "maybe one or two weeks then we will have found your hiding places and the heroes leading you"

3. I need some scenes which i could flesh out. At the moment i have:
Evil attacks the temple of the good deity, The rebels have to defend a bridge, some passageway some other buildings, because the evil forces push really hard and give not much time to rest.
If the PCs need some ideas to take the initiative, the Rebel leader gives some ideas for counterattacks which give the good guys some time to rest, new weapons or something like that.

4. Can there occur any trouble (for me as a DM) if the PCs try to send a spy into team evil ? Though i have to improvise quite much then i think. I think the PCs know that something like that could end with the dead if something goes wrong.

5. How could a scenery look like, if the evil forces send a spy to the rebels inclusive the betrayal ?

6. Team Evil has informations about the PCs because the Succubus already met them in an earlier adventure. A big advantage for Team Evil i want to use but not overuse. how can i get the balance ?

7. I as a DM has a "small problem" I gave my players the feeling "if i want to find you i will find you not the big matter where you are. Some secret organisations who want to stay undetected but also want to get in contact to the PCs. But not in the bad way like "There is no use in hiding, invisibility or the like because the opponents you have to take care off have the possibilities to detect you"
I hope you can understand what i want to say. So... how to take care of that problem if there is any

8. If they defeat all of the leaders, they still have to take care of the Chaotic Genesis Spell that surrounds the city, growing, until it surrounds the whole material plane. I thought of 7 Genensis orbs, hidden everywhere in the city. What could happen if they destroy one ? Or what do the PCs have to do to destroy them ?

Thanks for all ideas and hints you can give me

For #2, I think the best thing is to have the adventure end in a way that you're sure they'll be going back to the city. I think you have a great idea here, I just think it'd be cooler for it to be a surprise to them rather than a hackneyed cut-scene =)

For #4, the most difficult thing to deal with spies is how much you trust them. If a spy gets caught, if offered the choice between death and becoming a double-agent, it could be a really difficult decision. You could have your "spy" come back with enough information to make their trip credible, but you could have them act slightly more guilty than they were before the trip. Perceptive PCs will catch on that something is up, and if the PCs don't get the hint, you could have the bad guys assassinate the spy under mysterious circumstances to give the PCs another heads-up.

The same idea could apply to #5.

For #6, I would suggest over-using the info. I mean if these guys are wicked enough to conquer a city on their own, they should have really good sources of information. However, if she has knowledge that's too critical to destroying the party (like who would make good hostages, the wizard only uses fire spells, etc) you could go the route that the 3 BBEGs don't trust each other and share as little information with each other as possible. One of the PC/Rebel side's biggest advantages could be exploiting the in-fighting between the three forces. You know the old maxim about evil turning in on itself....

I'm not sure what you mean by #7...are you talking about coming up a way for the PCs to get in contact with the rebels?

For #8 its really up to you. I'm not familiar with this concept, but that sounds like something the rebel forces can handle if the PCs can handle the BBEGs.

What do you mean with: " I just think it'd be cooler for it to be a surprise to them rather than a hackneyed cut-scene =)" ?

I am sure that they will travel back. After they have left the dungeon they will see a city surrounded by a big multicolored globe. Or the Globe appears when they are on their way back. Under #2 i described the first scene the pcs will see when they enter the city. Or shouldn´t this scene exist ?
That i am going to let them find out it by themselves ?(fighting orcs, slaadi, see a BBEG maybe, and then finding the rebels who tell them whats up)

#4 (spy stuff) This will be hard. I think i am going to make some development notes for spy scenes and how the spy npcs will react: what could happen if the pcs are to passive, aggressive; different betrayal scenes. Spy stuff will be much freestyle then becaus i always have to react to the pcs actions.

#6 Background: The slaads wish: Be the owner of an own plane he can design (he uses the genesis spells)
Succubus wish: Finally getting to a place she can call her home. (she works together with the slaad)
Orc Leader: Conquering the Valley and the lands beyond.
The slaad succubus team, teamed up with the orcs. although slaad are very trong, they have not the big mass of fighters to overrun a town. But the orcs living in the north have it. => Team.
Nice idea with the turning evil on itself. The orcs could turn somehow against the slaad sucubus team. They won´t win if it comes to a big fight, but that will weaken the others very much.

#8(genesis spells) i took the idea from the 9th lvl psionic power Genesis.
(creates an astral plane you can design as you wish or an antiplane, destroying everything near it) I just gave it a chotic touch^^ (slaad live on the chaos plane on limbo) The rebels could handle it. But i think it would be very hard. The Rebel forces have an average lvl of 1-7 and only the rebel leaders are about lvl 9. I think it´s very hard for a 9th lvl character to deal with a 9th lvl spell. But they can help of course. (The Player Characters will be ~ Level 14-16)

What I mean about #2 is that if you have a scene explicitly telling the PCs what is happening in a corny cut-scene it takes a lot of surprise out of the plot, and it spoils the BBEG advantage. But I suppose if you want the city to have a huge multicolored bubble around it, it will be pretty obvious anyway.

In that case, if the takeover of the city is so obvious, then perhaps the PCs could come across another adventuring party just as they escaped the city, and give them some information that way. I find it extremely unlikely that the PCs will be able to find a spy to waltz into a giant multicolored bubble. Most people would probably stay away from it, so any entrant would be regarded as highly suspicious. I would suggest staying away from drafting different spying scenarios unless you have a lot of time, because chances are the PCs are going to want to try to do something completely different than you expect.

I guess I would ask, if the bizzaro city is so weird, then why are the Orcs still in the city? I mean, they've already looted it and everything, and its not like Orcs are not typically occupiers like Hobgoblins. Aren't they afraid of being mutated? A key plot point could be where the PCs frame/convince/intimidate (depending upon your players) the Orcs to leave or take arms up with the PCs. Heck, the remaining humans might even be willing to bribe the Orcs over to their side, or at least let them go free if they assisted against the Slaad/Succubi. Or if the city is tilted towards evil anyway, maybe they'd try to woo the succubus instead (wouldn't that be ironic). Or perhaps a remnant of humanity can be drawn out of the mutated beings to turn against their master, frankenstein-style.