Standard Empires(M12), Build Up Advice Needed!

First thing would be to try to make it as consistent as possible. Eliminate a lot of the 2x and 1x cards to put 4x of the things that matter more.

Maybe something like this:

Artifacts
3 Crown of Empires
3 Scepter of Empires
3 Throne of Empires
2 Tumble Magnet

Sorceries
4 Ponder
4 Preordain
2 Black Sun's Zenith

Instants
3 Tezzeret's Gambit
4 Mana Leak
2 Stoic Rebuttal
4 Doom Blade
2 Dismember

Lands
4 Drowned Catacomb
3 Jwar Isle Refuge
9 Swamp
8 Island

SB
3 Sorin's Thirst
3 Spell Pierce
1 Volition Reins
4 Spreading Seas
3 Flashfreeze
1 Consecrated Sphinx

The cheap deck filtering is your best friend in finding your Empire pieces and keeping mana open for your counter magic and instant kill spells.

I'd probably go to 3x each on the Empire pieces as you would like to naturally draw into them and curve out but you don't want to see them too often.

It seems like you are on a budget so I only put in the Core Set dual. If you can get Darkslick Shores they are great as well.

You have to play like a control deck as you assemble your pieces. Don't tap out if you don't need to.

The SB is pretty generic. Some cards to hate on Valakut, some more counters to protect your artifacts, a couple of cards to swap in to play more like a standard control deck.

Hope that helps!

1) If you can't afford Dismember then use some Go For the Throat if you have them. Otherwise move a few Sorin's Thirst from the SB to the MD so that you have the extra life cushion against aggro decks. Run the 2 Gambit's you do have and replace the 3rd with something like Jace's Ingenuity or 1x Diabolic Tutor to help you put the pieces together.

2) If Catacombs are too costly (I know around my area they are trading pretty low now after being reprinted again in M12 - something like $3 a piece here) Then I would go up to the 4th Jwar Isle like you stated but I would probably use Terramorphic Expanse instead of the Depths. Making sure you have the colors you need is more important than rearranging the cards. You should really try to invest in the better lands though; you'll be able to use them in EVERY U/B deck you ever make afterwards so even if they rotate next fall they'll still be useful.

3) The Magnet is there to help keep you alive while you put the pieces of your deck together. It'll hold off things like Titans and creatures equipped with Swords and would have synergy with the Gambits to give it an extra counter or two. If you don't want to use that, you might want something like Into the Roil which is useful for dealing with anything that hits the board that might cause a problem such as Planewalkers or Tempered Steel

The Shrine of Piercing Vision isn't bad, but you are better off just running actual card drawing cards instead since drawing the Shrine late might be too slow to be useful.

It might look slow, but 4 Ponder/4 Preordain and 3x other card draw will let you see a lot more cards than you think...

4) Life's Finale is slower than Black Sun's Zenith but it would do the trick. If you are running the Finale, then I would certainly want things like Magnet to help slow the other person down until you can get enough mana on the board to cast Finale.

again, hope this was useful!