Odin had the dwarf blacksmith under his command produce 9 medallions for 9 different warriors from 9 different worlds. He distributed these medallions to each great warrior to symbolize the peace between them. When the day came and the warriors died, the medallions were destroyed by an ancient magic so that the right people would find them. Whoever owns one of the coins will have the unique power of the coin. If you collect all 9 coins, you will be invincible.