South-west of Zao Steppe, a vicious raging mage has created a dimensional portal on top of a tower in order to access the energy buzzing there. The wizard himself is keeping the dimensional rift open. So as long as he is alive you are able to enter Another Dimension where you will encounter yielothax, strange and tough creatures with rare loot. Also, you might come across the Uniwheel, a very specific mount.
Killing yielothax will also weaken the raging mage and if a certain number of them has been slain, the raging mage can be defeated and you can get your hands on his unique loot. However, the dimensional rift will break down soon after killing the mage and players will have to leave the dimension until the raging mage will return and restore the portal.
Source: Tibia.com