Activate Ashnod's Altar by sacrificing Sun Titan.
When Sun Titan dies, Unholy Indenture triggers, returning Sun Titan from your graveyard to the battlefield.
When Sun Titan enters, it triggers, returning Unholy Indenture from your graveyard to the battlefield attached to Sun Titan.
Repeat.

Infinite colorless mana

Infinite death triggers

Infinite creature ETB

Infinite creature LTB

Infinite creature sacrifice triggers

Sun Titan

Ashnod's Altar

Unholy Indenture

Activate Bartolomé del Presidio by sacrificing Danitha.
When Danitha dies, Unholy Indenture triggers, returning Danitha from your graveyard to the battlefield tapped.
When Danitha enters the battlefield, it triggers, returning Unholy Indenture from your graveyard to the battlefield attached to Danitha.
Resolve the Bartolomé del Presidio ability, putting a +1/+1 counter on it.
Repeat.

Infinite +1/+1 counters on a creature

Danitha, Benalia's Hope

Bartolomé del Presidio

Activate Bartolomé del Presidio by sacrificing Brotherhood Outcast.
When Brotherhood Outcast dies, Unholy Indenture triggers, returning Brotherhood Outcast from your graveyard to the battlefield.
When Brotherhood Outcast enters the battlefield, it triggers, returning Unholy Indenture from your graveyard to the battlefield attached to Brotherhood Outcast.
Resolve the Bartolomé del Presidio ability.
Repeat.

Brotherhood Outcast

Activate Viscera Seer by sacrificing Boonweaver Giant
When Boonweaver Giant dies, Unholy Indenture triggers, returning Boonweaver Giant from your graveyard to the battlefield
When Boonweaver Giant enters, it triggers, returning Unholy Indenture from your graveyard to the battlefield attached to Boonweaver Giant.
Resolve the Viscera Seer ability from step 1.
Repeat.

Infinite scry 1

Boonweaver Giant

Viscera Seer

During your upkeep step, activate Mairsil using Hakim's first ability by paying {U}{U}, returning Unholy Indenture from your graveyard to the battlefield attached to Mairsil.
Activate Mairsil using Lion's Eye Diamond's ability by sacrificing it and discarding your hand, adding {U}{U}{U}.
When Mairisil dies, Unholy Indenture triggers, returning Mairisil from your graveyard to the battlefield.
Repeat.

Combos with "Unholy Indenture"