This is a combo deck based around Torgaar, Famine Incarnate.

The combo only requires 4 mana but requires the following setup.

You need to have at least 3 creatures in play, Gonti's Machinations and at least 2 energy.

This is not too hard to achieve as the deck has several cards which generate more than one creature and plenty of card draw.

The combo is then to cast Torgaar, Famine Incarnate for 2 black (sacrificing 3 creatures) and set your opponents health to 10.

Then, fling him at your opponent and finish them off with activating Gonti's Machinations.

In theory the deck can achieve this on turn 4 but it usually takes a bit longer to setup.

I'll go through some of the card choices:

Hope of Ghirapur helps to protect the combo as you can hit your opponent, sac it, and then execute the combo in your second main phase.

Dusk Legion Zealot is a cheap body which replaces itself with card draw but can also trigger Gonti's Machinations.

Weaponcraft Enthusiast is great value providing 3 bodies for 3 mana.

Filigree Familiar provides some health which helps against aggro and then card draw on death.

Ravenous Chupacabra is both removal and a body that can be sacrificed later.

Costly Plunder is the card draw engine in this deck, there are plenty of good targets to sacrifice.

Rite of Belzenlok is an alternate win condition with the big demon but also creates 4 clerics who can be used to block or to sacrifice.

Sideboard Cards:

Duress comes in against control to try and clear the way for Torgaar, Famine Incarnate.

Fungal Infection comes in if you are facing a lot of 1 health creatures. Being able to take them out and create a creature yourself is great value.

Golden Demise is for against go wide decks. It should be fairly easy to get Ascend.

Never // Return comes in when you need some more removal and the Zombie token can also be useful.

Supernatural Stamina comes in against damage and destruction based removal. A lot of your creatures have enter the battlefield effects which can be good to trigger again.

Lost Legacy is to try and take out key cards that could disrupt your combo, for example, Vraska's Contempt.