Cast Leonardo either from your hand or from the command zone by paying {W} due to its cost reduction.
Oketra's Monument triggers, creating a creature token.
When Leonardo enters, Angelic Sell-Sword triggers, creating a creature token.
Activate Phyrexian Altar by sacrificing Leonardo, adding {W}.
Put Leonardo into the command zone from your graveyard.
Repeat.

Infinite LTB

Infinite ETB

Infinite sacrifice triggers

Infinite death triggers

Infinite storm count

Infinite commander casts

Leonardo, Worldly Warrior

Phyrexian Altar

Angelic Sell-Sword

Oketra's Monument

Cast Whitemane Lion by paying {1}{W}.
When Whitemane Lion enters the battlefield, it, Angelic Sell-Sword and Arahbo trigger.
Resolve the Whitemane Lion trigger, returning it from the battlefield to your hand.
Resolve the Arahbo trigger, creating a 1/1 Cat creature token.
Resolve the Angelic Sell-Sword trigger, creating a 1/1 Mercenary creature token.
Activate Phyrexian Altar twice by sacrificing the Cat and Mercenary, adding {1}{W}.
Repeat.

Arahbo, the First Fang

Whitemane Lion

Cast Shrieking Drake by paying {U}.
When Shrieking Drake enters the battlefield, it and Angelic Sell-Sword trigger.
Resolve the Shrieking Drake trigger, returning itself from the battlefield to your hand.
Resolve the Angelic Sell-Sword trigger, creating a creature token.
Activate Phyrexian Altar by sacrificing the creature token, adding {U}.
Repeat.

Shrieking Drake

Activate Emiel the Blessed by paying {3}, blinking Felothar.
When Felothar enters the battlefield, it and Angelic Sell-Sword trigger.
Resolve the Angelic Sell-Sword trigger, creating a token.
Resolve the Felothar trigger, causing you to sacrifice a nonland permanent and put a +1/+1 counter on each creature you control.
Activate Crystalline Crawler by removing a +1/+1 counter from it, adding {1}.
Activate Cryptic Trilobite by removing a +1/+1 counter from it, adding {C}{C} that can only be spent to activate abilities.
Repeat.

Infinite +1/+1 counters

Felothar, Dawn of the Abzan

Cryptic Trilobite

Crystalline Crawler

Emiel the Blessed

Cast Ebondeath from your graveyard by paying {B}{B} due to Green Goblin.
Angelic Sell-Sword triggers, creating a creature token.
Activate Phyrexian Altar by sacrificing the creature token and Ebondeath, adding {B}{B}.
Repeat.

Norman Osborn // Green Goblin

Ebondeath, Dracolich

Activate Sadistic Hypnotist by sacrificing a creature, causing you to discard Basking Rootwalla and Blazing Rootwalla into exile.
Basking Rootwalla and Blazing Rootwalla's madness abilities trigger.
Resolve the Basking Rootwalla trigger, causing you to pay {0} to cast it from exile.
When Basking Rootwalla enters the battlefield, Cloudstone Curio and Angelic Sell-Sword trigger.
Resolve the Cloudstone Curio trigger, choosing to return nothing to your hand.
Resolve the Angelic Sell-Sword trigger, creating a 1/1 Mercenary creature token.
When the creature token enters the battlefield, Cloudstone Curio triggers, returning Basking Rootwalla from the battlefield to your hand.
Resolve the Blazing Rootwalla trigger from step 2, causing you to pay {0} to cast it from exile.
Repeat steps 4 through 7 one additional time using Blazing Rootwalla instead.
Repeat from step 1.

Combos with "Angelic Sell-Sword"