Activate Carrion Feeder by sacrificing Gravecrawler.
Deathgreeter triggers, causing you to gain 1 life.
Resolve the Carrion Feeder ability, putting a +1/+1 counter on it.
Cast Gravecrawler from your graveyard by paying 2 life.
Gravecrawler enters the battlefield, triggering Ayara, causing each opponent to lose 1 life and you to gain 1 life.
Repeat.

Infinite +1/+1 counters on a creature

Infinite death triggers

Infinite ETB

Infinite lifegain triggers

Infinite lifeloss

Infinite LTB

Infinite sacrifice triggers

Infinite storm count

K'rrik, Son of Yawgmoth

Ayara, First of Locthwain

Carrion Feeder

Deathgreeter

Gravecrawler

Cast God-Eternal Bontu either from your hand or from the command zone by paying {3}{B}{B} and commander tax, if applicable.
Endrek Sahr triggers, creating five 1/1 Thrull creature tokens.
The Thrull tokens enter the battlefield, triggering Carnival of Souls five times.
Activate Phyrexian Altar by sacrificing two Thrull tokens, adding {B}{B}.
Deathgreeter triggers twice, causing you to gain two life.
Resolve each Carnival of Souls, causing you to lose five life and add {B}{B}{B}{B}{B}.
Resolve God-Eternal Bontu from step 1.
God-Eternal Bontu enters the battlefield, triggering its first ability.
Holding priority, activate Phyrexian Altar by sacrificing God-Eternal Bontu, adding {B}.
God-Eternal Bontu's second ability and Deathgreeter trigger.
Resolve the God-Eternal Bontu trigger, causing you to put it into your library third from the top from your graveyard.
Resolve the Deathgreeter trigger, causing you to gain 1 life.
Resolve God-Eternal Bontu's first ability from step 8, sacrificing three Thrulls and drawing three cards.
Deathgreeter triggers three times, causing you to gain three life.
Repeat.
Once you have an empty library, you can continue the combo by only sacrificing one Thrull in step 13, and sacrificing the other two Thrulls to Phyrexian Altar.

Infinite card draw

Infinite colored mana

Infinite draw triggers

Infinite lifegain

God-Eternal Bontu

Endrek Sahr, Master Breeder

Carnival of Souls

Phyrexian Altar

Cast Yawgmoth by paying {2}{B}{B}.
When Yawgmoth enters the battlefield, Scurry Oak's evolve ability triggers.
Holding priority, activate Yawgmoth by paying 1 life and sacrificing a creature.
When the creature dies, Deathgreeter triggers, causing you to gain 1 life.
Resolve the Yawgmoth ability, putting a -1/-1 counter on Scurry Oak and causing you to draw a card.
Resolve the Scurry Oak trigger, putting a +1/+1 counter on it, triggering Scurry Oak's second ability.
Holding priority, activate Yawgmoth by paying 1 life and sacrificing a creature.
When the creature dies, Deathgreeter triggers, causing you to gain 1 life.
Resolve the Yawgmoth ability, putting a -1/-1 counter on Scurry Oak and causing you to draw a card.
Resolve the Scurry Oak trigger, creating a 1/1 Squirrel creature token.
When the Squirrel enters the battlefield, Scurry Oak's evolve ability triggers.
Repeat from step 6.

Near-infinite death triggers

Near-infinite ETB

Near-infinite lifegain triggers

Near-infinite LTB

Near-infinite sacrifice triggers

Yawgmoth, Thran Physician

Scurry Oak

Activate Tetzimoc by paying 2 life and revealing it from your hand, targeting a creature an opponent controls.
Horobi triggers, destroying that creature.
The Tetzimoc ability fails to resolve  due to no longer having a legal target.
The creature dies, triggering Deathgreeter and Blood Artist.
Resolve the Deathgreeter trigger, causing you to gain 1 life.
Resolve the Blood Artist trigger, causing target player to lose 1 life and you to gain 1 life.
Repeat.

Destroy any number of target creatures during each of your turns

Tetzimoc, Primal Death

Horobi, Death's Wail

Blood Artist

Combos with "Deathgreeter"