Bribe With Levels
Offer PC's secret deals from NPC's.
Have one of the PC's mentors explain to them.
You may gain power as a sorcerer (3 levels). Tell the player that these levels act like monster levels, and do *not* modify your ECL for experience purposes.
Only one hitch. If they tell *anyone* where this power comes from, they lose their powers.
Do this with each character, except make a different sort of deal with each one. Watch them




their eyebrows when fellow PC's do things and have feats that their normal levels won't allow. Watch the paranoia grow as each one of them accepted this near irresistable deal.
Watch a good party turn nuetral and eventually some turn evil to protect that which they bargained and now rely on for their power and further advancement.
Watch when they find out they are carrying portions of a powerful deity's soul. Watch as they are called to a ceremony to bind this evil deity. Watch them stare in horror when just as the deity's body appears, it asks the Lawful Good high priest, "Have you collected the portions of my shattered soul?"
Watch the Lawful Good high priest turn to the PC's and say, "Yes, the sacrificial vessels have come to worship at your altar." Watch them scramble as the binding sticks the acolytes are carrying are actually daggers designed to release the trapped spirits.
Watch as the players defenses to keep attackers out of the final ceremony keep them trapped in the temple with the evil acolytes as the great deity is taking shape, each time a player character is stabbed, it gains more of its power (the NPC sacrifices were stabbed first as an illustration to the PC's).
Watch them all accuse each other of making deals as they fight for their lives. Watch them all die, their powers weakened and stolen. Explain to the wizard that the archangel that might have saved them was trapped in his tower and he refused to free him because he was the bound source of power for this incredibly powerful tower. Explain to him and scroll that would have "released the power of the tower", sitting in his backpack now, and useless, was their key to salvation.
Watch nobody ever make a deal with the GM again and every time someone walks away with the GM, watch the other players give him the 3rd degree.
Execute this plan over a period of eight real months.
I'm a bastard.