Sadly after the pass of years is still no way to check it out. The way my friends and I checked it out was by killing the Energized Raging Mage for some random hours, until we received the message: "GNAAAAAHRRRG!! WHAT? WHAT DID YOU DO TO ME!! I... I feel the energies crawling away... from me... DIE!!!!.
Keep in mind that to kill it you must have to kill 250 Yielothax. Otherwise, you will get a message when you try to enter the tower when Raging Mage has spawned:
You have not proven worthy in the dimensional struggle against the yielothax.