Thinking about adding in some milling elements to the deck. I have a little room because I eliminated some cards.

Also considering removing Rooftop Storm because it isn't a very fun combo even when I just stumble into it.

What are your thoughts?

How about throwing in Tunnel Vision, naming Patriarch's Bidding, Zombie Apocalypse or Living Death could easily spell the end for opponents

Interesting additions might be Lim-Dul the Necromancer and Boneknitter because who doesn't want their zombies to stay on the battlefield?

Zombie Master would be pretty badass with Urborg, Tomb of Yawgmoth on the field. Not to mention that changelings are technically zombies so Shapesharer for instance can be an easily recurred legend killer, along the lines of your theme, Cairn Wanderer too could be handy.

Mimic Vat and Fleshbag Marauder is another combo i'd consider. Either one on their own is pretty nasty anyway.

Nightscape Familiar might be worth a shot in here too. Not too keen on Stormscape Familiar here though...

I had Fleshbag Marauder in a previous incarnation of the deck and took it out. Now I have much more recursion so I may add it in again. Mimic Vat could be fun with many cards in this deck. Think Rune-Scarred Demon, Geralf's Messenger, Geralf's Mindcrusher or any ETB effects in this deck in the Vat.

I like the idea of Shapesharer but i'm not too excited about Cairn Wanderer. I tihnk I would run Necrotic Ooze over the wanderer.

Thanks for the input.

Well, the ooze doesn't really have much in the way of offensive power, while the wanderer can potentially gain life, avoid removal, attack, stay untapped and evade blockers the turn it comes in. Ooze is more useful to a player with a creature based combo strategy.

Any thoughts on where to fit in Mimic Vat and Fleshbag Marauder? Also, where to fit in Shapesharer if you think he should really be in here.

Ghoul raiser and maalfield twins seem sub-optimal. Do they do anything in particular that more cost efficient cards wont cover?

Ghoulraiser could definitely be taken out because of the "at random" in his ETB. Maalfeld Twins has been nice because when I sac him I get some more tokens to sac later. Even for that he is kind of expensive.

I am considering putting Nim Deathmantle in the deck. Sacrificing and paying 4 to return a sac'ed creature to the battlefield would be pretty nice for a number of these creatures with ETB effects.

Also, Spirit Away could probably become Mind Control.

Took out Essence Harvest and Exhume for Mind Control and Volition Reins.

The very next game I played they both performed fantastically shifting the game in my favor. Here is a recap:

I was able to get out Rhystic Study on turn 3 right after an opponent cast Howling Mine. Since it was so early in the game Rhystic Study gained me at least 4 or 5 cards in the following turns. I had to pitch quite a few cards to get down to 7 during these early turns. Luckily I'm playing a zombie reanimation deck.

An opponent had a Luminarch Ascension and a Norn's Annex on the battlefield and would have been able to use Ascension on his next turn. I drew Volition Reins and stopped it.

Then another opponent resolved a Butcher of Malakir while playing a token deck. He was still trying to find his sac outlet when I stole it with Mind Control. From there I dominated the mid game. In response to an Austere Command naming enchantments I was able to sacrifice the Butcher to keep my opponent from using him for his diabolical schemes.

The game ended with the casting of Buried Alive tutoring a Wonder, Gravecrawler and Havengul Lich depositing them in my graveyard where they conveniently waited for my next turn. Next turn I cast Spirit Away targeting an opponent Crypt Ghast to double my mana production to absurd levels and cast Zombie Apocalypse.

All the zombies I discarded early game came back from the grave, as they should in any good zombie deck. This included a Havengul Lich which reanimated my opponents Butcher of Malakir, combining this with my double-black producing swamps, a sacrifice outlet, and Gravecrawler I cleared the board and swung for lethal on all players.

Keep the advice coming! This deck is performing much better than it has in the past.

I play tribal zombies using grixsis, but your deck looks soild. Maybe adding more mill and a Gravespawn Sovereign

I have considered Gravespawn Sovereign. I feel like I don't often have enough zombies to make good use of him. When I do have that many zombies I usually don't need his ability to win. I may need to just try it in the deck. Any suggestions on what to take out for it?

Considering Consuming Aberration, Nim Deathmantle and Filth. Anything you see in the deck that is unnecessary that these cards could replace?

Mind Control and the like Seems sub par and and the sovereign let's you get them from any grave yard. I would also run one less land.

Stolen Identity Is an over CMC'ed metamorph, because as a red play, I would destroy that creature super fast, and then its exiled.

And the twins are under performers with that caliber of creatures.

Cards that could be cut easily are: Maalfeld Twins, Ghoulraiser, Grimoire of the Dead, and maybe Disciple of Bolas

Cards being considered currently are:
Consuming Aberration which would be nuts with Gravecrawler,
Nim Deathmantle to use with my sac outlets and ETB effects,
Gravespawn Sovereign which I love its ability and flavor but only works with lots of zombies,
Liliana Vess which could also replace one of my tutors if I am having trouble finding space,
Sage of Fables doing double duty to keep reusing my undying creatures and get some card draw since Grimgrin will be a constant source of counters
Filth to get damage through

Your control magic seems a bit lackluster, I recommend any of the following changes.

Gilded Drake > Treachery > Control Magic > Corrupted Conscience > Mind Control > Spirit Away
Blatant Thievery > Take Possession > Volition Reins

I can definitely put Corrupted Conscience in for Spirit Away and Control Magic in for Mind Control. The other options are a little too expensive for me right now but I will put them in my Wants and see what happens.

I can also do Take Possession for Volition Reins.

Thanks for the input.

Maybe Animate Dead or Necromancy for Rise from the Grave?

Maybe put them both in. What should I take out for the second one?