From Prince Haaggkhen's Castle, head southeast to Hazhulkhen's Castle in the desert. (It's the castle farthest southeast on the entire map, and the only one this walkthrough has not taken you to yet.)
Hazhulkhen's Castle is actually a pyramid. Go ahead and enter and touch the second symbol from the left to deactivate the barriers. Exit north.
Kill the enemy in the room and exit west. There's nothing in the next room so just exit west again.
Use the Unlock spell to open the doors and exit north. There's nothing of interest in the room with the oven, so just go west.
Kill the enemy in the room, unlock the door, and head north. Nothing in the next room, so take the east exit.
Go north, cast Unlock in the next room, and go west.
Kill the Drakkhen Guard and cast Unlock, then exit west again. Kill the enemy in the next room and go north.
Take the north stairs in the room with the oven. In the next room prepare yourself for the final boss and when you think you're ready, exit north.
Prince Hazhulkhen, the final boss of the game, appears in this room. After talking to him, the battle will start. So long as your characters are on or about Level 10, and have fairly decent equipment, you should not have much trouble beating him. For what it's worth, he's only about as difficult as Prince Haaggkhen was. Once Hazhulkhen goes down, you will have all eight Tears, and a Priest will appear to tell you to go to the center of the world.
Leave the pyramid and head northwest, to the row of arrows in the middle of the Earth Area. When you get close, you 'll see the glowing arrows on the ground. Step into them and congratulations, you've won the game. Now you can just sit back and watch the ending.
GO TO PART 7: THE NINTH TEAR - ENDING SEQUENCE