Cast Rot Hulk by paying {5}{B}{B}.
When Rot Hulk enters, it and Necroduality trigger.
Resolve the Rot Hulk trigger, returning Fleshbag Marauder from your graveyard to the battlefield.
When Fleshbag Marauder enters, it and Necroduality trigger.
Resolve the Fleshbag Marauder trigger, sacrificing it and causing each opponent to sacrifice a creature.
Resolve the Necroduality trigger, creating a token copy of Fleshbag Marauder.
When the token Fleshbag Marauder enters, it triggers, sacrificing Rot Hulk and causing each opponent to sacrifice a creature.
Resolve the Necroduality trigger from step 2, creating a token copy of Rot Hulk.
When the token Rot Hulk enters, it triggers, returning Rot Hulk from your graveyard to the battlefield.
Repeat from step 2.

Each opponent sacrifices all creatures they control

Infinite creature ETB

Infinite creature LTB

Infinite creature tokens

Infinite death triggers

Infinite creature sacrifice triggers

Return some creature cards from your graveyard to the battlefield

Necroduality

Rot Hulk

Fleshbag Marauder

Cast Fleshbag Marauder by paying its mana cost.
When Fleshbag Marauder enters, it triggers, causing you to sacrifice it.
When Fleshbag Marauder 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.
Repeat from step 2

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

Vizier of Remedies

Cast Fleshbag Marauder by paying {2}{B}.
When Fleshbag Marauder enters the battlefield, it triggers.
Holding priority, activate Relic of Legends' second ability by tapping Burakos, adding {B}.
Burakos triggers, giving it and all creatures you control that share a creature type with it +2/+0 and undying until end of turn.
Resolve the Fleshbag Marauder trigger from step 2, causing you to sacrifice Burakos, and each opponent to sacrifice a creature.
When Burakos dies, its undying ability triggers, returning it from your graveyard to the battlefield with a +1/+1 counter on it.
Activate Retribution of the Ancients by paying {B} and removing the +1/+1 counter from Burakos, giving Fleshbag Marauder -1/-1 until end of turn.
Fleshbag Marauder dies as a state-based action due to having 0 toughness, triggering its undying ability, returning it from your graveyard to the battlefield with a +1/+1 counter from it.
Repeat steps 2 through 6 one additional time.
Activate Retribution of the Ancients by paying {B} and removing the +1/+1 counter from Burakos and Fleshbag Marauder, giving Fleshbag Marauder -2/-2 until end of turn.
Repeat from step 8.

Combos with "Fleshbag Marauder"