doctorhydrogen

Needs moar Nixix Cyclops

Though it's nice to have the option when someone else plays dickish.

Freed from the Real and/or Pemmin's Aura for multiple Niz taps per turn. Sigil of Sleep so whenever Niv pings someone it bounces a creature. Charisma to ping a creature and steal it with Niv? Not sure it'll work in your deck as well as mine where all the creatures are Tim-types, but when it rolls it rolls.

It's pretty cheese-ball though, and would get me pretty much hate-killed as an object lesson in my playgroup. YMMV of course. I run Curiosity in my Niv deck but there's a gentleman's agreement I don't play it on Niv, same with Ophidian Eye.

As I said, there's zero wrong with mono-black. I couldn't do it because Korlash is so boring as a commander, but that's entire me, and entirely aesthetic. The real problem is a lack of good tribal legends in mono-black. There's cool mono-white soldiers, cool mono-green elves, but mono-black zombies are kind of hurting for cool zombie legends.

Are you really married to mono-black? Not that there's anything wrong with it, but there's just so many cool zombie Commander options if you go b/g or b/u, not to mention it opens up fantastic zombie spells like Rooftop Storm, and another tribal booster in things like Diregraf Captain.

And while Cranial Plating seems nice in theory, I think in practice Fireshrieker might do more damage, and Whispersilk Cloak may guarantee it gets through.

Since white doesn't seem to be doing much, I'd consider moving to red instead. That way you could work in Atogs and Myr Retriever. Something Arcbound to the Atog, move the counters to another critter, sac the Retriever to buff the Atog further and bring the saccrified Arcbound whatever back to your hand. Prototype Portals are also dirt cheap and let you do the same tricks. Red also lets you play Volt Charge for removal combined with a counter proliferate.

I'd guess the "can only attack alone" bit on MoC may be ruled to make him an invalid target for Kaalia.

Agreed 100% on Declaration being unfun. I side-board it out when I'm not playing Rhys, but when someone plays a 1 or 2 mana general I don't feel bad using it.

A couple of random cards that would fit

- Telepathy: I've had an opponents in multiplayer counterspell another opponent's removal attempt because they are okay with everyone but me seeing their hand if they can see the other two hands. YMMV there, but it's a fun, cheap (in all senses) and useful card. No idea what I'd drop for it though, and I fully admit it's entirely a personal preference kind of card.

- Declaration of Naught: My common EDH opponents tend to play cheap-casting Generals, and DoN is great to keep Rhys the Redeemed or Gaddock Teeg or Nin, the Pain Artist from being immediately replayed three seconds after you kill it.

- Capsize: Replayable Boomerang

If you're gonna go for a Metamorph why not just put in a Vesuvan Doppelganger? Same price (cash-wise) and in EDH the mana cost probably won't matter much.

Not to mention EDH tends to be multi-player, or at least it does near me, so you're looking at milling three people not one. Still, nice try at a deck, and it might be cool if you're just playing 1v1.

In running a similar deck I found Rooftop Storm to not really be useful. By the time I had enough mana to cast it I had so many fatty zombies out being able to cast the one left in my hand for free (though it's not really free since you need to pay for Rooftop Storm in the first place) really didn't matter. YMMV there.

IMO hard to pass Call to the Grave here, and I'd use Sleep over Crippling Chill, but that's also a matter of taste.

I'm a huge fan of budget decks, and half the fun sometimes is just putting them together using cards you have. HOWEVER, if one was looking to tweak the deck still using budget cards here's where I'd go:

Prison Term or Obliv Ring over Arrest. Same mana cost in a mono-white deck for both, and Prison Term gives you the flexibility to move to a bigger threat, and Obliv Ring gives you the flexibility to lock out a Planeswalker or artifact.

You could probably pick up 4 Puresteel Paladin and still keep the total deck under 12 bucks, too. I've seen them for just under a dollar each, and they absolutely wreck in a deck like this.

Argentum Armor is a great card and an EDH staple, but I'm not sure if it's fast enough here, same with Grappling Hook. Gorgon Flail maybe?

I'd have a tough time building an unblockable deck and not including 4c Curiousity and 4x Sigil of Sleep.

Isn't Sol Ring banned in Commander?

Capsize over Spin Into Myth, imo. It's dirt cheap to buy if you don't have it (like a quarter online) and you can recast it each turn for six mana which is pretty easy to have available. I'd be very tempted to use Spell Burst for the same reasons. Buyback kicks so much tail in Commander.

Since you don't seem to have rogues, Neurok Stealthsuit over Cloak and Dagger? You lose the +2/0, but it's cheaper to equip, and the ability to equip at instant speed for two blue mana (and thereby make a targeted creature untargetable) is pretty huge.

Evil Eye deck, that's ten kinds of fantastic

4x Nature's Lore over Rampant Growth. They're still dirt cheap to buy if price is an issue, and the land coming into play untapped is huge. I'd also be very tempted to swap 4 Kodama's/Cultivate/Search for 4 Skyshroud Claim. One more mana to let you drop both lands directly into play untapped is worth it, and they're cheap to buy price-wise, too.

2x Natural Affinity perhaps? Also maybe 2x Fruition? In this kind of deck it could essentially be 10-12 life for one mana. That's a tough call, though. You could also try to procc Khalani Heart with Terramorphic Expanse-type sacc lands, but for this deck that seems too complicated.

Swap Tutor for Increasing Ambition. It's dirt cheap online, and for one extra mana lets you pull two more cards via flashback. I'd probably swap Regrowth or Recollect for the Treasured Find, both are under a buck, though since you're not running Elixir of Immortality maybe the exile portion of Treasured Find is irrelevant.

Disturbed Burial maybe? Buyback kills in EDH. I'd keep an Exsanguinate at least in a sideboard. In a multi-player EDH game that can swing you 30 life easily.