This is a budget mono black demon deck. The goal of this deck is to cast our big demons as early as possible and to beat our opponent with them.

So our demons are Demon of Catastrophes, Abyssal Persecutor, Bloodgift Demon and Shadowborn Demon. Two of them require sacrifices and Abyssal Persecutor needs to be sacrificed to allow us to win. Because of that we have a big sacrfice theme in the deck.

Spark Harvest and Disciple of Bolas allow us to sacrifice our creatures in addition to our demons mentioned earlier. They also provide a lot of utility.

Also, we have a lot of small creatures that we can sacrifice in order to cast all of those sacrifice needy card. Burglar Rat, Orzhov Enforcer and Dusk Legion Zealot all serve this purpose.

Another good card is Ritual of Soot which allows us to clear the board without removing our demons. For the big creatures that it doesn't remove we have Shadowborn Demon and Spark Harvest to deal with them.

Finally since there is a lot of lands in the deck because we want to hit 4 lands by turn 4, I added Barren Moor so that our hand doesn't get swamped in the late game.