You've got ways to steal things fromm graveyards, but few ways to make sure there's goodies there to take. You'd probably want to add some mill, as it also lets lazav change into something useful or deadly. We're talking the house mill cards like Consuming Aberration, Altar of Dementia, Altar of the Brood, Memory Erosion, and maybe Dreamborn Muse. I'd also recommend Dimir Doppelganger and Evil Twin since they are versatile creatures that fit the copy/steal theme.

Your deck seems nice but i think you need some nice ways to draw cards too, Brainstorm Thought Scour seem nice ways to do it

I agree with WhatTheNether, Thought Scour seems perfect for your deck.

However, overall a very cool deck, made me wince multiple times seeing the cards and combos :)

Tezzeret the Seeker and Trinket Mage to retrieve some of your artifact?

Tormod's Crypt and Bojuka Bog for some graveyard hate (with tormod retrievable with tezzeret -0).

Rogue's Passage Thassa, God of the Seabecause we dimir love unblockables ;)

Mindcrack Mesmeric OrbKeening Stone if you want more mill.

This is my Lazav deck, more oriented on milling, I hope it will be useful to you Lazav: Mill & Copy since 2013, feel free to ask questions or comment :D

Thank you for the feedback! Some very good points has been made.

I have added Consuming Aberration and Memory Erosion as mill options.

I have added Altar of Dementia as a way to terminate desserters (If I can't have your creatures, no one will have them!).

Bojuka Bog has replaced a swamp for some graveyard hate.

Leyline of Anticipation has been added for more flexibility.

I will probably add Thassa, God of the Sea when I get my hands on one.

@TheHamihaze Since I have cut some of the artifacts, and some of them are next in line, I'll stay clear of Tezzeret the Seeker for now. Thanks for the suggestion, though :)

If you're into stealing things and playing mind games, drop in a Sphinx Ambassador. Your curve is also a little high, and if I were to cut something for the sphinx, it'd be Mindleech Mass because you're far more likely to hit something impactful with the sphinx.

As jmzimmer stated your CMC is a bit high and you have little mana rocks / ramp.do you really need Kozilek, Butcher of Truth and Jin-Gitaxias, Core Augur?

Maybe you can swap them for Mirko Vosk, Mind Drinker and Phenax, God of Deception or Nemesis of Reason, or if you want them to discard Windfall Dark Deal Whispering Madness or for more mana Chromatic Lantern Gilded Lotus

I'm always a fan of Chromatic Lantern although when you only have two colors it's not quite as necessary, so to help pay for all of your big spells I feel that Gilded Lotus is a good choice to add to your deck if you can find the space.

@jmzimmer I like the Sphinx Ambassador and I'll try and find room for it.

I also like the Mindleech Mass as it gives me direct card advantage (opponent loosing a card) and virtual card advantage (I get his card).

@TheHamihaze I don't excatly need Kozilek, Butcher of Truth or Jin-Gitaxias, Core Augur, but I figure they belong in a deck with Omniscience in it? I guess this is my only opportunity to play win-more cards like that. :)

Regarding mana rocks and accelerators, I think I have quite a few options. Would you add more?

Rocks- Basalt Monolith- Coalition Relic- Mana Vault- Sol Ring- Thran Dynamo

Accelerators- Burnished Hart- Solemn Simulacrum- Cabal Coffers & Vesuva

Can be both- Acquire- Sculpting Steel- Blatant Thievery- Bribery (though highly unlikely)

Also Quicksilver Amulet is usefull, even though it won't net me 4 cards with Kozilek, Butcher of Truth

@Rune_Hoejsgaard good points on Omniscience and Quicksilver Amulet, for some reason I completely missed those two.

The only things I don't see are counterspells and mass removal here, but other than that I think it's a solid deck, +1 :)

Squeeze in Rings of Brighthearth? With Basalt Monolith, that's infinite colorless mana. Theoretically this would let you use Blue Sun's Zenith to deck people you don't like. :p

Blades_of_Autumn, I believe that that is against the rules because Rings of Brighthearth say "if it isn't a mana ability" and one of the definitions for a mana ability is if it will put mana into your mana pool upon resolution.

@ArcaneEmperor See Rings of Brightearth and Basalt monolith for an explanation of the combo.

I don't like the combo since it is very opaque, but I'll investiage if I can include the ring in other combos or fallback combos. Thank you for the tip @Blades_Of_Autumn

Yeah, sorry, I just asked a friend about it and he explained it. I should have thought of that since I run a Derevi deck, but I just overlooked it.

Included Thassa, God of the Sea and Sphinx Ambassador. I'll upgrade Diabolic Tutor with a Vampiric Tutor when I get my hands on some extras.

After an annoying game with only graveyard recursion cards in my hand, I've decided to replace a few of them with some milling. I'm thinking Mesmeric Orb and Mindcrank (as suggested by TheHamihaze) for Beacon of Unrest and an Island?

I would definitely agree with putting in Mindcrank for Beacon of Unrest and if you feel your mana base has been solid in games then Mesmeric Orb has some definite value for your deck, however make sure you're prepared for the hate that's going to bring on you, especially if you have your commander out, obviously.

Updated with more milling, as discussed. Replaced Diabolic Tutor with Vampiric Tutor

Any other obvious upgrades?

I'm surprised there isn't a Swiftfoot Boots, Lightning Greaves, or Whispersilk Cloak in here. All easy ways to make sure your opponents can't target your stuff. And not to mention making Mindleech Mass unblockable is an added bonus.

Hey, I've made a Lazav deck on the same concept. You should check it out for any ideas that you might have missed. Good luck. Lazav, Dimir Master of Mine.

@SirFowler I've always been a fan of the boots, but I could not find room for it in the deck. What, if anything, would you cut to make room for some boots?

I have never had success with Whispersilk Cloak (it always seems to be too expensive for what it does), so I think I'll skip on that for now.

Cheers

@Rune_Hoejsgaard I'm not the biggest fan of Sphinx of Magosi. Sure you have the ability to draw multiple cards and pump him up, but you already have plenty of card advantage that isn't as costly as the sphinx. Not only that, but it takes 3 islands just to cast him AND 3 colorless. You already have the Phyrexian Arena, Necropotence, etc., so I don't think such a costly card is truly worth it.

You may or may not enjoy combos, but Duskmantle Guildmage loves Mindcrank.

Reliquary Tower is a must.

I've got a pretty neat dimir deck with the same commander. The theme is the same, although it is slightly less competetive and costs about $350 cheaper. I've got a lot of cards, both in the main deck and maybeboard, that could give you some ideas. You should check it out.

http://tappedout.net/mtg-decks/lazav-the-clone-commander-edh/