Activate Wall of Blood by paying 1 life, causing it to get +1/+1 until end of turn.
Repeat step 1 until Wall of Blood's power is equal to the highest life total among your opponent.
Activate Jarad by paying {1}{B}{G} and sacrificing Wall of Blood, causing each opponent to lose life equal to Wall of Blood's power.
Each opponent loses the game due to having zero or less life.

Each opponent loses the game

Near-infinite lifeloss

Jarad, Golgari Lich Lord

Wall of Blood

Declare Jumbo Cactuar as an attacker, triggering its ability, giving it +9999/+0 until end of turn.
Activate Jarad by paying {1}{B}{G} and sacrificing Jumbo Cactuar, causing each opponent to lose 10,000 life.

Jumbo Cactuar

Activate Phyrexian Devourer's second ability by exiling the top card of your library, causing you to put a number of +1/+1 counters on Phyrexian Devourer equal to that card's mana value.
Repeat step 1 until Phyrexian Devourer's power is greater than each opponent's life total.
Phyrexian Devourer's first ability triggers.
Holding priority, activate Jarad by paying {1}{B}{G} and sacrificing Phyrexian Devourer, causing each opponent to lose life equal to Phyrexian Devourer's power.

Near-infinite damage

Phyrexian Devourer

Cast Hatred by paying {3}{B}{B} and by paying life equal to the highest life total among your opponent, causing any other creature you control to get +X/+0 until end of turn, where X is the life paid this way.
Activate Jarad by paying {1}{B}{G} and sacrificing the creature, causing each opponent to lose life equal to the creature's power.
Each opponent loses the game due to having zero or less life.

Hatred

Activate Jarad by paying {1}{B}{G} and sacrificing Serra Avatar, causing each opponent to lose life equal to Serra Avatar's power.
Each opponent loses the game due to having zero or less life.

Serra Avatar

Activate Jarad by paying {1}{B}{G} and sacrificing Soul of Eternity, causing each opponent to lose life equal to Soul of Eternity's power.
Each opponent loses the game due to having zero or less life.

Soul of Eternity

Cast Demonic Consultation by paying {B}, naming a card not in your library and exiling your library.
Activate Jarad by paying {1}{B}{G} and sacrificing Cosmogoyf, causing each opponent to lose life equal to Cosmogoyf's power.

Exile your library

Cosmogoyf

Demonic Consultation

Activate Jarad by paying {1}{B}{G} and sacrificing Angelic Enforcer, causing each opponent to lose life equal to Angelic Enforcer's power.
Each opponent loses the game due to having zero or less life.

Enduring Angel // Angelic Enforcer

Activate Phyrexian Devourer by exiling the top card of your library.
Repeat step 1 until your library is empty or the number of cards you own in exile is equal to or greater than each opponent's life total.
Activate Jarad by paying {1}{B}{G} and sacrificing Cosmogoyf, causing each opponent to lose life equal to Cosmogoyf's power.
Activate Phyrexian Devourer's second ability by exiling the top card of your library, causing you to put a number of +1/+1 counters on Phyrexian Devourer equal to that card's mana value.
Repeat step 1 until Phyrexian Devourer's power is greater than each opponent's life total.
Phyrexian Devourer's first ability triggers.
Holding priority, activate Jarad by paying {1}{B}{G} and sacrificing Phyrexian Devourer, causing each opponent to lose life equal to Phyrexian Devourer's power.

Cast Leveler by paying {5}.
When Leveler enters, it triggers, exiling your library.
Activate Jarad by paying {1}{B}{G} and sacrificing Cosmogoyf, causing each opponent to lose life equal to Cosmogoyf's power.

Leveler

Activate Arc-Slogger by paying {R} and exiling the top 10 cards of your library, dealing 2 damage to any target.
Repeat step 1 as desired. It is recommended to do this until your library is empty or until the amount of cards you own in exile is greater than or equal to each opponent's life total, whichever comes first.
Activate Jarad by paying {1}{B}{G} and sacrificing Cosmogoyf, causing each opponent to lose life equal to Cosmogoyf's power.

Combos with "Jarad, Golgari Lich Lord"