I didn't succeed at making a cheap deck like I wanted, but it's cheaper than the commander deck I had my eye on and it is (probably) mostly functional as monoblack aggro. I tested it a bit on MTG Arena's Historic, though not with all the same cards and obviously not against Modern decks, but it does hold up rather well there.
This has a slightly better than 50% chance (53.8% actually) of having 4 mana on turn 4. Odds of land on turn 5 are pretty low, at only 36.7%, but we don't run anything over 3 mana anyways.
From turn 4 on we should be able to keep mana open to activate Relentless Dead in response to a boardwipe, which makes us pretty resilient.
Overall, the sideboard should be considered a huge WIP here. I am not super familiar with Modern's meta or what I should be trying to answer with it.
Right now I have just selected a sideboard that I feel might do what I need it to do.
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