This is not a deck to win. This deck is a joke. However, should you somehow pull this off it will be janky, ridiculous, and hilarious. But should you make it to turn five and begin the process of combo-ing off, you'll clear the board of all your enemy's creatures and make yourself an army of zombies. Here's the step by step guide:

Turns one through four: Just play lands. If you somehow miss a land drop, start playing the lottery because that's stupidly unlikely.

Turn five: Play your fifth land, cast Sidisi, Undead Vizier to have her exploit herself and tutor for Ad Nauseum.

Turn six: Play your sixth land, cast Ad Nauseum and draw your entire deck. This will cost you up to thirty-one life if you've drawn none of the combo pieces so far. The following is the step by step of the combo. There's not much flexibility alas so I recommend having the list on hand

Play Ornithopter and tap your last untapped land to cast Culling the Weak and sacrifice Ornithopter. Net you'll have 4 black mana.

Dark Ritual --> 6 Black Mana

Zombie Infestation --> 4 Black Mana

Discard 12 swamps to Zombie Infestation to make 6 zombies. This puts enough cards in the graveyard for Threshold.

Cabal Ritual --> 7 Black Mana

Ashnod's Altar --> 4 Black Mana

Sacrifice six zombies to Ashnod's Altar --> 4 Black Mana, 12 Colorless Mana

Mutilate --> 2 Black Mana, 10 Colorless Mana

Rain of Filth, Sacrifice six swamps --> 7 Black Mana, 10 Colorless Mana

Discard 68 swamps to Zombie Infestation to generate 34 zombies

Inverter of Truth --> 5 Black Mana, 8 Colorless Mana

Coat of Arms --> 5 Black Mana , 3 Colorless Mana

Whip of Erebos --> 3 Black Mana, 1 Colorless Mana

Mogis's Marauder --> 1 Mana

From there you should be set. You'll have an army of gigantic Lifelink zombies with some even having haste to swing out right away.

If you actually want to win a game, replace everything but Ad Nauseum and Dark Ritual with the sideboard. It's a bit of a cheap win condition but it works.