I also run a very similar deck that has been performing very, very well. I agree with clark1424 on the casting costs issue and running fewer Risen Executioner. I have tested Nantuko Husk and he can be very powerful in this deck. However personally I have decided to move him to SB since he wasn't all that good except for against white exile crap.

I would strongly suggest running Gisa and Geralf. This card takes zombie decks to the next level and IMO is necessary. Compelling Deterrence is also extremely used both offensively and defensively. Last one is Dark Salvation. Extremely useful for a removal spell and to gain more zombie tokens. you can also cast it for just 1 black mana and usually kill almost any creature if you have enough zombie son the board.

All in all very nice deck. Check mine out for some suggestions if you like White Walker Hoard. +1 from me

Personally I'm unsure about Voldaren Pariah  ^Flip in this deck but if you still want to keep her in I would at least IMO remove -2 Voldaren Pariah  ^Flip for +2 Diregraf Colossus. Also I would remove Sinister Concoction for more Compelling Deterrence.

spraysPaint tale a look at round 16 of the protour. It was zombies vs temur emerge. Do you see a single diregraf colossus there? Then look at how many Voldaren Pariahs there were. I will remove a conoction and something else for a couple morbid curiosity's once Kaladesh comes around

now this is almost the same deck that I'm running with. I just swapped Sinister Concoction with 2 Wharf Infiltrators and 1 more Grasp of Darkness. Also, i did swap instead of 1 Jace, Vryn's Prodigy  ^Flip with 1 Distended Mindbender, 1 Stitchwing Skaab with 1 Compelling Deterrence (to make sure that if a Virulent Plague manages to get in the board), 1 Relentless Dead for 1 Elder Deep-Fiend for punching through enemy defenses (was thinking of 1 Graf Harvest actually, and 2 of your Diregraf Colossus into 2 Liliana, the Last Hope.

This is a good deck though... I personally would recommend removing Diregraf Colossus. Yes it can be as big as 6/6 or 7/7 for 3 drop and it can generate zombie tokens from each summons, but i honestly it best fits pure casting zombie decks with Gisa and Geralf, Nantuko Husk and Fleshbag Marauder.

I think that card is made for such decks to abuse graveyard "casting" rather than recursion through abilities.

Overall, id rate your deck 8/10

clark1424, yeah... This deck is just with the stuff that I have lying around. If I had infiltrators, I would gladly put them in. Same with the grasp and Lilianas ($46 buck tcg-mid! No wonder I don't have any!). When I get them, I'll put them in.