SirKalma

First off, I would take out any infinite combos that you have - it takes the fun out of the game when you do that. It's one thing to keep it as a last resort, but if you're planning on utilizing it as much as often, you should probably take it out.

That being said, you should probably put a blade splicer in there. Replace the lands such as Azorius Chancery with Shock lands or Dual lands. Sunblast Angel could also be helpful. Terastodon can also be quite brutal, especially if you flicker him out to destroy your opponent's lands.

Lastly, you're missing a card from your deck.

I would take out Dissipation Field. I used to run it in one of my decks until somebody kept flashing a Bogardan Hellkite in, taking advantage of the card's ability.

You probably also want to stick Ward Sliver in there, it's a nasty little thing.

You should throw in a Cabal Coffers for a combo with Urborg, Tomb of Yawgmoth.

Murkfiend Liege would be helpful for this deck, as would Prophet of Kruphix.

It's an EDH deck.

I would take out Prognostic Sphinx and Restoration Angel, because Restoration Angel is most helpful with flicker decks, and I only see it being useful with Grave Titan and Iona. Prognostic Sphinx's scrying ability is helpful, but with Rhystic Tutor, you'll have static card draw and it won't be necessary. While its hexproof ability is nice, I don't see much reanimation within the deck. Also, in regards to Jace, Mind Sculptor, I would test out the deck with him in it, and see how it fares. I've noticed that his effectiveness varies upon what kind of deck he's in.

Should you decide to put in Blightsteel Colossus, I would be very careful before dropping him if you're in a large multiplayer match, because players will automatically come after you once they see infect.

Well, there's cackling counterpart, which you can flash back if the token gets killed, but I would recommend Phyrexian Metamorph, just because you can have it come into play as an artifact or a creature. That being said, you don't really have too many artifacts in here, you may want to consider Blightsteel Colossus, Platinum Emperion, Thran Dynamo, possibly a Grim Monolith/Basalt Monolith + Power Artifact combo, Lich's Mirror, and Norn's Annex. I would also replace Impulse with Rhystic Study.

That's what's been most effective for me in the past, although any sliver commander will automatically garner a lot of hate at the table.

Have you considered utilizing Galvanoth?

Why is Serra Avatar not in here? Also, you probably want some version of Clone in here, because you can clone Oloro, then send the original Oloro back to the command zone, and be gaining 4 life per turn instead of your regular 2. I would take out the lands that are similar to Azorius Chancery, they just set you back, mana wise. Exsanguinate is also very effective, especially in combination with the Urborg, Tomb of Yawgmoth + Cabal coffers combo, or the Power Artifact + Grim Monolith/Basalt Monolith combo.

I would not play Sliver Overlord as your commander - should an opponent take control of him, they can take control of your other slivers, and you won't be getting them back unless you manage to get Sliver Overlord back.

Where are the tutors? Also, you may want to consider taking out Purphoros, because while he is helpful, I only see potential in using him in combination with Sheoldred. I would take out the amulet of vigor + lands such as izzet boilerworks, you'd be better off utilizing the shock lands or dual lands, because you can't guarantee that you'll get amulet of vigor, and you don't want to be encountering any mana setbacks with the large creatures you have.

Where's the Urborg, Tomb of Yawgmoth + Cabal Coffers combo? You'll be able to get your big creatures out faster that way. Fetch lands would also be helpful.

Unless you're intending for this to be a 1-on-1 EDH deck, I would take out true-name nemesis. It's a great card in 1-on-1, but I haven't seen it used very effectively in multiplayer matches. Also, the Kiki-Jiki + Zealous Conscripts combo is going to draw a lot of hate at the table (but that's okay, I run it too - it definitely works), just be aware of that. You also need some creature removal, such as damnation or killing wave.

You might want to take a look at my thraximundar deck (I assume that's your general, right?) to see if there's anything in there that you like/could improve upon.
http://www.mtgvault.com/sirkalma/decks/thraximundars-throne/

Well, she's definitely effective, as is Blazing Archon, but he's pricey, I'm not sure if you would want to put him in.

Out of curiosity, why did you not opt for Teysa, Envoy of Ghosts?

Have you considered putting Serra Avatar in here, what with all the life gain there is?

Thanks, I'm trying to figure out something to replace Zedruu and Bazaar Trader with, though. Any suggestions?

You definitely need to replace the things like Selesnya Sanctuary with shock lands or dual lands. Fetch lands wouldn't hurt, either, but they're not necessary.

Well, Zealous Conscripts + Kiki Jiki, Mirror Breaker kind of does the same thing as a pestermite combo. Wheel of Fortune does sound like a good idea, I'll figure out something to take out, possibly preordain or ponder.

Have you considered Magma Sliver?