If you're not sold on Doomed Dissenter you could swap it out for a couple Phylactery Lich paired with some Desecrated Tomb You have a fair amount of return from the graveyard so you end up with an indestructible beater and it's safety net creates bodies for every graveyard return. Granted it doesn't immediately help the early game, but it is an option

Hey, If you keep it mono black (as I would recommend) get your hands on some Cabal Stronghold as they is the best reason to run mono black. Demon of Catastrophes is a budget version of Doom Whisperer especially in this deck as you have sacrifice-able creatures :).

Lotleth Giant works best with Liliana, Untouched By Death and 4 Stitcher's Supplier I would highly recommend both of those cards with this deck. I was playing Arena and hit my opponent for 12 life with Lotleth Giant and a graveyard full of zombies thanks to Sticher's Supplier.

As above said it really is worth playing Cabal Stronghold

Vicious Offering or Severed Strands I would say are a better replacement for Moment of Craving

Also 2-3 Desecrated Tomb would go nicely in this deck.

Ritual of Soot might be something to consider for the main or sideboard it's a good boardwipe

TrashWolf95 Thank you for your comment and suggestions. 1. I got 4 Cabal Stronghold , which I will include soon. Maybe more Josu Vess would work too... 2. Moment of Craving will leave the deck, but I'm not sure, if I want other removals like Walk the Plank or maybe 2 strong creatures like Josu Vess, Lich Knight

My main issue with most suggestions is, that the card are M19 or older and will leave standard in some months. I don't feel like buying planeswalker for example, if I can't use them for some time. Otherwise Desecrated Tomb, Stitcher's Supplier and Liliana, Untouched By Death are great cards.

Lets hope for some zombie cards in january...

Ixalan through M19 won't rotate until Fall of 2019. That is the better part of a year and plenty of Magic to play still. I understand the rotation concerns, but I think you've got some time to put this together and really play it out so you better know what you can use from the new set.