Activate Kenrith's fifth ability by paying {B} due to Agatha, returning Jirina from your graveyard to the battlefield.
Activate Relic of Legends' second ability by tapping Jirina, adding {B}.
Activate Jirina by sacrificing it.
Repeat.

Infinite LTB

Infinite death triggers

Infinite sacrifice triggers

Infinite ETB

Kenrith, the Returned King

Relic of Legends

Agatha of the Vile Cauldron

Jirina, Dauntless General

Activate Jirina by sacrificing it.
When Jirina dies, Luminous Broodmoth triggers, returning Jirina from your graveyard to the battlefield without a flying counter on it due to Solemnity.
Resolve the Jirina ability.
Repeat.

Solemnity

Luminous Broodmoth

Activate Jirina by sacrificing it.
When Jirina dies, its persist ability triggers, returning it from your graveyard to the battlefield without a -1/-1 counter on it due to Vizier of Remedies.
Resolve the Jirina ability.
Repeat.

Eirdu, Carrier of Dawn // Isilu, Carrier of Twilight

Vizier of Remedies

Activate a basic Swamp by tapping it, adding {B}.
Activate Kenrith's fifth ability by paying {B} due to Agatha, returning Jirina from your graveyard to the battlefield.
Activate Earthcraft by tapping Jirina, untapping the basic Swamp.
Activate Jirina by sacrificing it.
Repeat.

Earthcraft

Activate Jirina by sacrificing it.
When Jirina dies, Ratadrabik triggers, creating a token copy of Jirina that is a 2/2 legendary Zombie in addition to its other types.
Resolve the Jirina ability.
Repeat using the Jirina token

Ratadrabik of Urborg

Leyline of Singularity

Cast Jirina by paying its mana cost if it is in your hand. Otherwise, activate Tayam by paying {3} and removing three counters from creatures you control, causing you to mill three cards and return Jirina from your graveyard to the battlefield with a vigilance counter on it.
When Jirina enters the battlefield, Metastatic Evangel triggers, causing you to put a +1/+1 counter on Cryptic Trilobite and Basking Broodscale and a vigilance counter on Jirina.
Basking Broodscale triggers, creating a 0/1 Eldrazi Spawn creature token that enters with a vigilance counter on it.
Activate Cryptic Trilobite by removing a +1/+1 counter from it, adding {C}{C} that can only be spent to activate abilities.
Activate the Eldrazi Spawn by sacrificing it, adding {C}.
Activate Tayam by paying {3}, removing both vigilance counters from Jirina and another counter from a creature you control.
Holding priority, activate Jirina by sacrificing it.
Resolve the Tayam ability, causing you to mill three cards and return Jirina from your graveyard to the battlefield with a vigilance counter on it.
Repeat from step 2.
Repeat.

Infinite self-mill

Infinite proliferate

Tayam, Luminous Enigma

Metastatic Evangel

Cryptic Trilobite

Basking Broodscale

Activate Jirina by sacrificing it.
When Jirina dies, Yedora triggers, returning Jirina from your graveyard to the battlefield face-down as a Forest land.
When Jirina enters the battlefield, Zimone triggers.
Holding priority, activate Jirina by tapping it, adding {G}.
Resolve the Zimone trigger, turning Jirina face-up.
Resolve the Jirina ability from step 1.
Repeat.

Combos with "Jirina, Dauntless General"