Hi woody_aaron! Blue Black Zombies is a really popular combination right now, and it looks like your deck has some really good zombies and zombie synergy in it. With just a few small changes we can make the deck both more consistent and more competitive.
To make this more consistent, we need to take a lot of the cards that we just have 1 of, and figure out how to get 3 or 4 copies of the best ones. This will increase our chances of drawing our best zombies. The cards that stand out that we should try to gt more of are
Negate (very powerful
counterspell that stops our opponent from using removal on our zombies, casting a board wipe, or laying down a powerful enchantment),
Compelling Deterrence (nice bounce spell that can let our zombies get through our opponents defenses, and forces our opponent to discard something if we have a zombie, which we usually will),
Pilfered plans (populates our graveyard and lets us draw extra zombies),
Gurmag angler (with all the ways to put stuff in our graveyard, this should be easy to cast for 1 or 2 mana. 2 copies would be plenty),
Lamplighter of Selhoff (can be a nice finisher, plus lets us filter through our deck and add stuff to the graveyard for
Gurmag Angler),
Drunau Corpse Trawler (Can make our zombies deadly, and lets us go wide),
Containment Membrane (anything that stops our opponents creatures is worth having in multiples), and
Relentless Dead (one of the best zombies available right now. A little pricey though, so if you can't get more no problem, we'll work with one). If we got one more
Negate,
Pilfered Plans, Lamplighter,
Drunau Corpse Trawler and
Gurmag Angler we'd be in nice shape. If we could get at least 2 more
Compelling Deterrence and
Containment Membrane, that would also help with consistency a lot!
Now that we're adding as many as 10 new cards, we need to make some cuts. The other one-of cards would be the easiest place to start.
Returned Reveler (not bad, but not great either),
Startled Awake (nice for a mill deck, but doesn't really fit our theme),
Earwig Squad (without other rogues, we'll never get the prowl, so he won't be able to be used to his full potential),
Returned Centaur (another just okay card that we don't need if we're only running as a 1-of),
Creeping Dread (unless we get a Madness sub-theme going, I think this will hurt us as much as our opponent),
Annul (great sideboard card, but
dead often enough to not run in the main deck),
Grim Guardian (with only 2 enchantments, his ability won't go off very often), Corpsesweft (these are pretty cool... and frankly, if we cut the one
Gurmag Angler, we could keep these in. Otherwise, they step over each other and we won't be able to get the max effect out of either card), and
Just the wind (good card, but for us,
Compelling Deterrence is just better). That makes a total of 11 cuts. From there the deck should now look something like this:
//Land
11
Island11
Swamp1
Blighted Cataract23 total
//Creatures
3
Rottenheart Ghoul2
Stitched Mangler2
Lamplighter of Selhoff2
Drunau Corpse Trawler3
Rancid Rats2
Gurmag Angler2
Thraben Gargoyle1
Relentless Dead17 total
//Spells
3
Shamble Back2
Macabre Waltz2
Grotesque Mutation2
Alms of the Vein2
Negate2
Pilfered Plans3
Containment Membrane4
Compelling Deterrence20 total
Looking at this, it looks like our creature count is now a little low. We can fix that by trading in some spells for more creatures.
Alms in the Vein really wants to be in a Madness / Discard heavy deck, so we should be okay letting it go for another pair of
Stitched Mangler.
Shamble Back is good, but 3 feels like too many (especially since we don't want to be removing our own creatures and taking Gurmag food), so if we swap 1 for a 4th
Rancid Rats, our creature count should be much better.
Finally,
Rottenheart Ghoul is just so much mana for 2 attack, and we're pretty light on low mana cost zombies, so replacing the three with something like
Crow of Dark Tidings (which will give us some flying protection and feed our graveyard),
Diregraf Colossus (since we're all zombie, this guy can get very powerful!), or
Prized Amalgam (will trigger off your
relentless dead, plus 3/3 is really nice) would give us more power to work with.
This is just one way to go though, but by doing something like this, I think you'll find the deck working significant;y more consistently. I hope you found this helpful! good luck and Happy Hunting