How to save a corrupted king?

[Ecliptic]

So, here's the scenario -

Have a party of ~8 adventurers. One of those adventurers is a prince of a dwarven kingdom. He left home because his father was getting greedy. Years later, the party returns with said prince and finds that the king has grown even more greedy. The kingdom is lavish and inlaid with gold and gems. Outlying towns are desolate from taxation etc. The king and queen emanate some sort of evil, and the king has an ornate golden staff (we think it can turn things into gold a-la-king midas... possibly the corrupting influence). A hole has opened up in the quarry and said hole leads to the underdark where a cult is trying to resurrect a tarrasque. We have dealt with the cult, but the tarrasque corpse remains and is slowwwwwly regenerating. The king doesn't care about the tarrasque (we'll probably have to find a way to get rid of it or fight it later). All of the king's sons have been killed in one way or another, and he does not care - he actually says that he wants to rule forever and he is happy that they are gone. He says that our companion is the only remaining threat to his rule. The king was not always so evil/dark/etc.

We have: a ranger (said prince), warlord (PoW), bard, sorcerer, fighter, cleric, slayer, monk (sometimes a wizard, sometimes another sorcerer, sometimes a barbarian... though these 3 are not there often).

What do you think we should attempt to do? Currently, we are enclosed in the throne room with the king and a bunch of his royal guards. More than likely, we can kill them all... though the possibility of the king turning people into gold is a bit unsettling.

[Kish]

Either incapacitate him, or, better if you can do it, arrange a temporary truce. Then use divination magic to find out the source of what's happening to him, because it sounds like there's certainly some kind of nasty magic here.

[Mr Adventurer]

What level are you?

[Komatik]

Mindrape.

10chars

[Diarmuid]

Could try a simple protection from evil to try and block any mental control bench exerted on him.

If that doesn't work, trying to detect magic and identify any auras on him might give more information.

Definitely tread carefully as you're outsiders in his realm where he can probably do whatever the heck he wants lawfully.

If you can get out of the throne room without a fight, maybe try finding some sympathizers to the prince and get more information about when this all started and what else was happening at that time.

[Ecliptic]

What level are you?

Group is level 9

[Kelb_Panthera]

Gather the peasants and any dissaffected nobles and military leaders, kick off a civil war (gonna happen with or without you if things keep up like this), then commit a proper coup detat and have the dwarf take his rightful place on his father's throne. Obviously.

[Gwazi Magnum]

If things break out into a fight? Cast Protect Evil and break for it.
You might win the initial fight, but you may not last against a vengeful Dwarven Kingdom (even if the King's a ****. The initial reaction is going to be "Kill the murderers!").

If you can get out peacefully? Or escape the fight and not be the most wanted people in the Kingdom?
Do what you want to learn more about the Staff. Consult Wizard towers for advice, ask friends of the prince about when and how it showed up, find a resistance group that most likely formed in all this and use their contacts and resources etc.