What illusion spells do I need to make this encounter work?

[killem2]

Short of it is, I have three players returning to an area with 5 other players who have never been here before.

THe three that were here, clearly saw a Huge Black dragon before they were teleported out of the area, and their two cleric leaders were left to fight the dragon.

They also in this room saw 6 groups of animated skeletons (past adventurers) that sang and danced to music generated from illusions, the subterranean area has been remade into an extravagant ball room.

In the back through a 20 ft wide opening, into a 70ft round enclave is the dragon hoard. The first time this was shrouded in darkness and the dragon came out.

This time, I want the opening to be well lit, but all the gold in there, I want it to actually look like old rotten food, and corpses and such, so it appears to the returning party that there was never a dragon here.

Just what kind of mass scale Illusions am I going to need?

[Jeff the Green]

Depends on who's producing them. A lot of casters with ghost sound, ventriloquism, and silent image could probably do it.

[Jett Midknight]

It really depends on how powerful you want the Illusion to be. Something like Permanent Image would be good as it stimulate smells, but has the downside of being permanent. If you want something a little less powerful Major Image is good as it also produces smells, but it will be dispelled upon touch/attack. Another option might be Persistent Image, as you can then script the illusion to do or say what you need it to do.

[killem2]

This is basically what I'm working with:

Mature Adult Black Dragon / Sorcerer 7 / Psychic Warrior 3.

If I can't run off pure illusion, is it possible to cast more than one hoard gullet spell?

Its only a level 2 spell so I can spare those slots I think.

I just wanted to have access to at least one polymorph spell so the dragon can try and bluff the party into thinking its a captured adventurer who is in need of help.

Then I could hide any trace of their being a dragon here on a basic level.