As a long time commander player, I hate taped lands. They really get in the way when you need fixing early and they just plain suck with a bounce-land in your hand. As much as people harp about non-basic lands in commander, basic lands can be better than a tap lands about 70% of the time, it's more about the quality of the non-basic land than just that it's non-basic. I prefer to fix with rocks like the signets or chromatic lantern for a 3+ color deck, and then run good consistent lands. If I do run tapped lands the vivid lands are better in 3+ colors. Also, the duels you need to run are the B+U/W, because your deck is so much more B than the other colors, you can almost think of them as a splash, you'll pretty much always want black but an Azorius Guildgate maynot be that helpful. If you can afford it the best land you could get would be Urborg.
The deck looks great! +1 from me.
Have fun out there!

Thanks for the feedback, passascats!

I'll definitely be scrutinizing my mana base as I finally start playtesting this. I want my commander early, so I wanted to give myself a good chance of having access to every color by turn 4 or 5. I went with as many lands/artifacts as I could that can produce all 3 colors.

Because blue and white are like a splash, I tried to treat them like one color, putting in lands that can produce either of them. There are no blue/white cards here (save for my commander), so I'll never need to produce both simultaneously.

Some good lands to add that are not to expensive for your deck might be Isolated Chapel, Drowned Catacomb and Glacial Fortress. Otherwise just run some more basic lands instead of those tapped lands, even in three colours that is in my opinion a better optioin.

Also for the zombies, you should run Noxious Ghoul and one of my favourties Corpse Harvester a great tutor and sac outlet. In combination with Gravecrawler that card is just amazing.

A good add for card draw might be Phyrexian Arena a bit expensive and hard to find but the card is so good almost an auto include for any black deck I make. I hope you can use these recommendations.

MatthijsTreuren, thanks so much for the suggestions!

I'll definitely consider the lands. After receiving two comments about upping the basic count, I'm really going to have to consider that. I'm going to do some research and learn why that's better.

As for the zombies, I've considered them all multiple times! Noxious Ghoul seems like it would produce board wipes less reliably than my Archfiend of Ifnir, and it can hit some of my humans and demons. Sidisi, Undead Vizier seem better to me than Corpse Harvester, as it's an ETB trigger.

I have been thinking of card draw enchantments like Phyrexian Arena, and will put more thought into it after more playtesting.

Have you considered Patriarch's Bidding ?

Kapitein_Koekblik, I have not, but it's a bit pricey dollar-wise, and only costs less for an effect quite similar to that of Zombie Apocalypse, except it allows others the opportunity to return their creatures as well. I prefer the flavor of the latter, and I like the potential for removal there as well. Thanks for giving me something to consider!

FiveEightFiveBC That's fair enough. I mostly use Patriarch's Bidding as a finishing move if I stacked my entire graveyard with zombies. Even more with cards like; Vengeful Dead, Wayward Servant or Plague Belcher. One of the more fun combo's would be Endless Ranks of the Dead + Tombstone Stairwell. Tokens created with the Stairwell work well with the cards managed above to ping your opponents to dead or they can function as an excellent sac outlet for cards like Nantuko Husk and Grimgrin, Corpse-Born etc

I'll consider them in the future. I have noticed how helpful the 2/2 tokens can be. I've been thinking about putting more token-producers in. Awesome suggestions :)

Hey, i love what you got going on here! +1! If you have the time,go on and check my version of Varina:

The Queen of the Dead thanks! And great build!