Clearly, there’s tools for it now.
[scryfall]Dromoka’s Command[/scryfall] and [scryfall]Back to Nature[/scryfall] is going to be a problem for this deck, because this deck is going to use plenty of enchantments, but who cares? Its monoblack.
First, we need a curve or sorts. There’s one 1-drop that’s an easy choice: [scryfall]Bloodsoaked Champion[/scryfall]. Others… not so much. Not that you need any. This format is slow, and you aren’t trying to kill fast, so its just a good, resilient threat, like many of the other cards in the deck.
Other creatures we might want? For 2-drops, the [scryfall]Despoiler of Souls[/scryfall] is a good start, but I’d like to play some [scryfall]Pain Seer[/scryfall]s as well. Sure, this is going to hurt against burn and other fast decks, but we’ll have lifegain, so no problem there.
For 3-drops Liliana is nice, but we’ll need more. Probably [scryfall]Herald of Torment[/scryfall]. I love that card. Its just pretty bad right now, at least in my home meta.
For 4-drops… [scryfall]Titan of Erebos[/scryfall], maybe [scryfall]Erebos, God of the Dead[/scryfall] himself as well.
Then, of course, [scryfall]Gray Merchant of Asphodel[/scryfall].
Spells? [scryfall]Sign in Blood[/scryfall], of course. It’ll help us draw cards for the Titan and it will also play the part of [scryfall]Underworld Connections[/scryfall] a little bit. Maybe one [scryfall]Read the Bones[/scryfall] as well. Of course, some removal and maybe a [scryfall]Whip of Erebos[/scryfall] or two.
4 Bloodsoaked Champion
4 Despoiler of Souls
2 Pain Seer
3 Liliana, Heretical Healer
4 Herald of Torment
4 Titan of Erebos
4 Gray Merchant of Asphodel
4 Sign in Blood
1 Read the Bones
2 Whip of Erebos
3 Murderous Cut
2 Hero’s Downfall
4 Bloodstained Mire
4 Polluted Delta
For sideboard, maybe a few lands (so that you can take out the painful draw and not lose because you can’t draw lands. Probably a somewhat transformative approach couldn’t hurt either. We have plenty of lifegain already, so you don’t probably need any of that. Some discard for control decks would be nice too.