You have the giant seer's doing the very sexy and erotic dance but for some reason you have them dressed badly. I think you should put the seer's in thongs. Maybe add a giant stripper pole next to the crystals.
Then instead of dropping collectables, the mobs in the quest could drop paper money. In order to keep the seer dancing you would need to stuff these bills into the thong. This way groups couldnt bypass mobs as they would need a supply of money to destroy the crystals.
If you collect enough money it should give you access to a secret "champagne room".