THE CORRUPTED ELEMENTS
THE CORRUPTED ELEMENTS
You can talk to Tommy right after you return from the Last City. He has some good news for you: he unlocked the Shrines of the four Elements, so you can finally go in and restore the Corrupted Elements, as Lady Stadi asked you to do some time ago.
But talk to the Captain next to Tommy first, he has some additional information for you, which you might want to follow up on.
THE GOBLIN ARMY
Go to the right towards the area of the Shrine of Terra. You may have been there before, during your first visit to The Pit. There are lots of goblins in those caves, maybe you can attract their attention and lure them into the swinging axes near the door. Anyway, have fun with them, they're all yours! I'm sure you can take on an entire army of goblins on your own by now. Don't forget to collect their Restore Health potions btw.
Go into the cave through the second door on the left, you'll find an advance party of legionnaires there, accompanied by an Ordinator Captain. You'll also see that the passage beyond is blocked by a magic wall; the Captain will explain to you that you need to restore the Elements to clear the way. So that is your first priority now.
TERRA TENEBRAE
Now that we're in the Terra part of The Pit, we might just as well restore the Element of Terra first. The order in which you restore the Elements is not important though, it's your decision.
Terra Tenebrae is an underground tunnel complex, and quite a maze. Levitation doesn't work in here, so if you fall into a pit you might never get out...
The quickest way through is to go straight ahead and follow the winding passage until you get to a junction, then go right. Follow that passage to the end, and you'll see a large cave. There are a couple of Demon Skeletons and some ordinary ones, but two of those are out of reach and shoot arrows at you, a bit annoying if you don't have ranged weapons yourself.
Go into the building down at the far corner, kill/avoid/ignore the lich inside, and go to the altar to take the Key to the Shrine of Terra. Also don't forget to look inside the urn in the corner for some potions of Jump - much needed in this place!
Now go all the way back to where you started, and to your right (facing the entrance door to Terra Tenebrae) you'll see another passage in the dark that you might have missed earlier. Go in and follow it to the end. That's where you may need one of those potions of Jump, because it's very difficult to climb - but not impossible; I tried it once, but you have to figure out where to put your feet.
You'll see a cave with stone arches and some dark clouds. I would avoid those if I were you... And the arches too, but I think you know how to spot the spear traps by now. Go right and around through the arches without stone floors beneath them, and check out the buildings. In one of them (the northeast one) there's an altar with something on it called Dark Terra, it would be a good idea to take some. (More on this in Ignis Tenebrae.)
On the far side of the cave there's a door to the Shrine of Terra, your destination. No more battles or intricate traps, just a deep, deep pit. In this cave you can levitate though, so there shouldn't be a problem.
At the bottom you'll see a blue crystal and a row of bells. As Tommy told you before you went to the Last City (read your journal), the altars in each Shrine are "captured", and that blue crystal is what's capturing it.
Touch the crystal. Memorize the sequence, and play the same tune on the bells. If you have a lot of trouble with this (I have, I never get it right the first time), I can help you: if you number the bells from 1 to 6, 1 being the biggest bell, then you need to play the sequence 1-6-3-4. This will free the altar, and you can touch it to restore the Element of Terra.Now leave the caves and go restore another one, if you haven't finished all four of them yet!
AQUA TENEBRAE
I'll take you to Aqua Tenebrae now. The entrance is almost at Tommy's feet, behind a fountain downstairs, but you know that already, of course.
There's no fighting to be done here, only a puzzle. Just stand still for a moment, and look around you. Of course you need to avoid those revolving potato mashers, or tenderizers, or maces, again, but you can go around them if you run to the far right of the room at the right moment. Then go down into the water, the maces can't touch you as long as you keep hugging the wall.
Now swim around a bit and look at the structure. There's a path you can follow, up the stairs and then onto the large beams - you can't levitate here, you'll have to walk - and watch out for those maces again up there! - all the way to the top, but there's nothing you can do there yet, there's only a blue flame and a message about a blessing.
If you actually walked all the way up to see that, don't walk all the way down again, just jump into the water! Fun, isn't it? Now go under water beneath the maces and look for a sphere called Chaos (this should remind you of the one in the Realm of Aqua, of course), in front of the tower base. Touch it and go to the top of the tower (again). You'll see a couple of swinging axes; just let yourself be "blessed" by them. The blessing takes you to the Shrine of Aqua.
If you have been to another altar before, you'll know what to do; for those that haven't, I'll repeat it here.
As Tommy told you before you went to the Last City (read your journal), the altars in each Shrine are "captured", and that blue crystal is what's capturing it.
Touch the crystal. Memorize the sequence, and play the same tune on the bells. If you have a lot of trouble with this (I have, I never get it right the first time), I can help you: if you number the bells from 1 to 6, 1 being the biggest bell, then you need to play the sequence 6-4-2-1. This will free the altar, and you can touch it to restore the Element of Aqua.Now get out of Aqua Tenebrae by going around the other (west) side of the maces, jumping up and running to the door. You can restore another one now, if you haven't finished all four of them yet!
AER TENEBRAE
You may have trouble finding the entrance to Aer Tenebrae, but it's right above the entrance to Aqua Tenebrae. Look up, it's only partly obscured by a small cloud.
Levitate (or jump high) to it and enter. There's only a Winged Twilight to deal with, the rest is easy. Just follow the path and go through the door of the Shrine, then run to the far side of the enormous hall.
If you have been to another altar before, you'll know what to do; for those that haven't, I'll repeat it here.
As Tommy told you before you went to the Last City (read your journal), the altars in each Shrine are "captured", and that blue crystal is what's capturing it.
Touch the crystal. Memorize the sequence, and play the same tune on the bells. If you have a lot of trouble with this (I have, I never get it right the first time), I can help you: if you number the bells from 1 to 6, 1 being the biggest bell, then you need to play the sequence 6-3-1-5. This will free the altar, and you can touch it to restore the Element of Aer.You can restore another one now, if you haven't finished all four of them yet!
IGNIS TENEBRAE
This is the last one I'm going to take you through, although it may be your second one, or the third... Go left from where Tommy is and descend down the stairs and the ramp. You'll see two statues beside a double gateway. The right one, the Passing of Time, will shock you a little; the Passing of Light is better.
You could take a look in the chest, you may find something nice. (Although I only found a gold coin - one - and a Nordic Fur Right Bracer just now. Yeah! 
) As you approach the lava stream, a statue will start to move across it (unless you visited this place before). Don't be scared, it won't do anything else... Now walk along the lava stream, to your left you'll see a door: this is the entrance of Ignis Tenebrae.
You'll be entering some dark caves and passages again. If you stand still for a moment, you'll hear a flame atronach. Follow the winding passage (left, then right) and go into the first passage on the right. Take care of that flame atronach if it gets in the way and walk up to the Anvil of Ignis. Touch it, and you'll get a message about needing some items: a Hammer of Fire (which is around here somewhere), and something called "the Darkest Earth, born at the altars of Terra Tenebrae". Once you have both, the anvil will produce a key.
Now may be a good time to leave this place and go to Terra Tenebrae to get that Darkest Earth, or Dark Terra, if you don't have it yet. (I'm not going to say it twice!)
Go back through this passage and go right, then left; you'll see a large room on fire, just like Tafall in the Realm of Ignis. If you go left into another room, you'll find the door to the Shrine of Ignis, but you can't enter it yet. Go the other way first.
The south passage is lined with statues, and you'll have to run the gauntlet here. I hope you are pretty fireproof, I expect that High Elves will have a rough time here... But you can rest and recover inbetween the pairs of statues if you want. Be careful at the other end, there are a couple of flame atronachs waiting for you in that room, who'd love to take advantage of your weakened state.
There's an altar in the room with the Hammer of Fire on it. Take it. If you don't have that Darkest Earth yet, now's the time to go to Terra Tenebrae and get it. (Oops, I said it twice! 
)
Go back to the Anvil of Ignis and simply touch it (don't equip the Hammer, that won't work) to get the Key of Ignis. Now go to the room north of the room on fire, and through the door of the Shrine of Ignis.
You may know what to do already, because you have at least been to Terra Tenebrae now. But just in case you didn't restore the Element of Terra yet, or any other, here's what to do.
Touch the crystal. Memorize the sequence, and play the same tune on the bells. If you have a lot of trouble with this (I have, I never get it right the first time), I can help you: if you number the bells from 1 to 6, 1 being the biggest bell, then you need to play the sequence 5-1-3-2. This will free the altar, and you can touch it to restore the Element of Ignis.You can restore another one now, if you haven't finished all four of them yet!
Have you restored all the Elements now? Don't bask in your glory yet! There's one more thing you need to do, and that's finding the mastermind behind all the troubles, to face up to him - or rather, just kill him. He's inside the Black Mill.