Once you have successfully defeated the first nine dungeons, you will not only gain access to dungeon 10, but to the tower, too. The tower can be reached via the "Dungeons" menu button.
In the tower you have three companions by your side, with whose help you can fight your way up to the 100th floor of the tower.
The highlight of the tower is that you can increase your gold bonus by 1% per floor cleared, and you receive epic items for your companions.
The maximum level of the companions can only be as high as the level of your own character.
Epic items found in the tower cannot be thrown in the toilet and do not give gold when sold in the store.