Mono Black "Infinite" Combos
Yes Mono Black has it all, in case you were wondering. Ususally this type of combo would be hard to set up because it requires so many pieces, but this deck is the exception.

Main pieces required for combos:

K'rrik, Son of Yawgmoth , Razaketh, the Foulblooded , Songs of the Damned , Elixir of Immortality , Shadowborn Apostle ,

Thrumming Stone is not needed but works alot easier, because you can clear the whole library in less steps. The below example will follow the "What does the deck do" section in the primer to stay on the main strategy.

Spell Steps:

Cast K'rrik, Son of Yawgmoth

Cast Thrumming Stone

Cast Shadowborn Apostle to start the triggers... getting shadowborn apostles out

Sac Shadowborn Apostle to dig card:Razaketh, the Fouldblooded out

With card:Razaketh, the Fouldblooded dig out the remaining pieces Songs of the Damned , and Elixir of Immortality

Choose your infinite

Plunge into Darkness Sacrifice all but maybe 5 Shadowborn Apostles (just in case you need to tutor interaction) to gain life. The life gain isn't the main reason but the shorter step to getting all the shadowborn apostles into the graveyard.

Cast Songs of the Damned This should pool more than 20 Black mana into the Mana Pool.

Cast chosen infinite

Side Note: * At this point LIfe, Mana, +1/+1 counters have already been played, move to step 10. at this time.

Cast Elixir of Immortality This will reshuffle graveyard into library. After you cast your infinite, Activate Elixir and Repeat steps 3 - 10.

Infinite Mana: K'rrik, Son of Yawgmoth , Razaketh, the Foulblooded , Songs of the Damned , Elixir of Immortality , Shadowborn Apostle

Infinite Graveyard Recursion: K'rrik, Son of Yawgmoth , Razaketh, the Foulblooded , Songs of the Damned , Elixir of Immortality , Shadowborn Apostle

Infinite Steal Opponents Cards: Main pieces + Praetor's Grasp

Infinite Life: Main pieces + Plunge into Darkness or Aetherflux Reservoir or Elixir of Immortality

Infinite +1/+1 Counters on K'rrik: K'rrik, Son of Yawgmoth , Razaketh, the Foulblooded , Songs of the Damned , Elixir of Immortality , Shadowborn Apostle

Infinite Counter..ish spell: Main pieces + Imp's Mischief (It should be stated that you can recure the spell repeatedly but you can not cast elixir at instant speed, unless you activate Emergence Zone

Basically these are redundant, if you have the main pieces on the field... you have probably already won. That being said it's always good to have back ups in case your combo gets interupted. This was originally made to be resilient to Counter Spell decks, by adding Elixir of Immortality .. After one cEDH game where every combo I played got countered ... Actions needed to be taken.

This is generally not included in the deck but if you want to have fun you could swap out Praetor's Grasp or Secret Salvage and replace one with card:Temporal Extorsion. Thats a weak card that does nothing and the opponent can just pay life....

Infinite Turns: Main pieces + Temporal Extortion ( if they pay the life... Activate Elixir of Immortality and start over again). Also note you can play Emergence Zone and sac to five spells flash every turn also.
Possible Turn 1 Win
Turn 1 opening hand A:

Swamp

Dark Ritual (3 Black Mana)

Mana Crypt (3 Black Mana 2 Colorless Mana), Cast K'rrik, Son of Yawgmoth 4 mana, 6 life

Shadowborn Apostle 2 life

Culling the Weak 2 life (5 Black Mana)

Thrumming Stone 5 mana

Shadowborn Apostle 2 life

Directions: - Cast cards in hand in that order. When you have gone thru the deck and gotten all your Shadowborn Apostle on the field There is 33 Shadowborn the deck has a 98% chance to pull all of the Shadowborn Apostles out

Tutor Razaketh, the Foulblooded

After Razaketh, the Foulblooded is on the field you should be able to win the game without interruption, you just pick how you want to win

See Win-Cons

Turn 1 opening hand B:

card:Aincient Tomb (2 Colorless Mana)

Mana Crypt or Mana Vault (4 Colorless Mana) Cast K'rrik, Son of Yawgmoth 4 mana, 6 life

Blood Celebrant 2 life

Thrumming Stone 15 life with Blood Celebrant

Shadowborn Apostle 2 life

Open, but maybe an extra Shadowborn Apostle just in case

Open

Directions: - Cast cards in hand in that order. When you have gone thru the deck and gotten all your Shadowborn Apostle on the field There is 33 Shadowborn the deck has a 98% chance to pull all of the Shadowborn Apostles out

Tutor Razaketh, the Foulblooded

After Razaketh, the Foulblooded is on the field you should be able to win the game without interruption, you just pick how you want to win

See Win-Cons

The turn 1 can be done with multiple fast mana options. Let me know what you see.

https://www.moxfield.com/decks/aNP220bVBUqjT7hIeVffDA/primer
https://tappedout.net/mtg-decks/phyrexian-chef/