I completed all the quest soloing with 3 different characters, a ranger, priest, & a mage. I went through 5 times on each character. I illed all the bosses, & all enimies in the cave. I collected 5 keys each time. I ty to go into the final area to fight main boss, stone says you didnt find the key. You need the key to enter. I had 5 keys. I had also tried it later with one of my guild masters in a party, & still, same thing. This quest has a bug or something. I gave up. Lame.