The following Wikipedia page is an excellent resource for those curious about the mythological underpinnings of the area: ( http://en.wikipedia.org/wiki/Tartarus )
* Affects: fly, sustained breath, ability to recall
Tartarus is the underworld to which the spirits of the dead, particularly those who worshipped the Olympian Gods, were escorted by the god of death known as Thanatos.
In the Underworld, souls are judged by Rhadamanthus. Depending on the outcome of the court, those judged in favor are taken to the Elysian Fields, and those who are found guilty are taken to Tartarus, which is found in the depths of the earth and is the place where the guilty pay for their crimes.
Hades always lived locked up away in his city of Erebus, which was covered by motionless clouds and eternal mist. Tartarus covered a vast area underneath
the Earth, beyond the borders of the visible world and even more beyond the river Oceanus. There is growth and vegetation in this dark land but its plants don't grow and the land isn't fertile.
Every hero is accepted into the Underworld, but nobody could get away from the terrifying guards, the Erinyes, and return to the upper world.
If you go past the TheGuardiansLair then you can't walk out of Tartarus, and if you are alone and don't know what you are doing, you are likely to die.
I will try and put together a summary of each area after you pass the guardian, but I am still learning them myself. I can say that this is quite a challenging area and at least at this point I would say you need at a minimum 2 people. You can get in and out safely alone, but you won't be able to kill many of the mobs in Erebus. With patience one can kill all mobs in the areas prior to Erebus solo.
I like hand-holding guides to the areas especially since the only people who learn all the secrets play all the time and talk amongst themselves, but not to people who play rarely. Plus, once an area is explored that needs multiple people it is difficult to get people to go back to that area. I changed the above to be set up as a series of links much like the Inferno walk-through.
If you don't want to know secrets and how-to's, don't click on the links.