In the land of Ardyl, there is a village that is running out of food. If you talk to the Mayor, he will ask you to recover the Horn of Plenty for them. Continue exploring Ardyl until you find the entrance for level 1, and down there you will run into a ghost, Riken, who went down into the dungeons to look for the horn, but died in the attempt, he will help guide you through the next couple of levels. Then down on level 2 you will have to fight a fire golem, and collect its sphere of fire. Level 3 brings you to an ice golem, who is the keeper of the ice sphere. Both of these spheres will be needed on level 4, when you run into a large room, with no door, just run around the perimeter of the room, and Riken should appear. You will need to give him the spheres, which he uses to bargain with the spirits of the stone, and then he gives you the Cloak of Clouds, which allows you to pass through the stone walls of the room. As soon as you put the cloak on, you will be attacked by a wizard (you don't have to keep the cloak on, you can just put it on, then change back to your ordinary armour, but still be allowed to pass through the stone).

After you have defeated the wizard, take the horn of plenty back to the Mayor of the village, and then as you're walking out of the village, Riken will appear and give you the Crystal of Wisdom.

Tip: You can collect up to 255 chicken legs from The Horn of Plenty before giving it to the Mayor, just right click on it. Thanks to Steven Dare for providing the limit.