Cast Peregrine Drake by paying {4}{U}.
When Peregrine Drake enters the battlefield, it triggers itself twice due to Panharmonicon.
Resolve one Peregrine Drake trigger, untapping five lands.
Activate those lands by tapping them to add at least {3}{U}.
Resolve the remaining Peregrine Drake trigger, untapping five lands.
Activate those lands by tapping them to add at least {3}{U}.
Cast Man-o'-War by paying {2}{U}.
When Man-o'-War enters the battlefield, it triggers itself twice due to Panharmonicon, returning itself and Peregrine Drake from the battlefield to your hand.
Repeat.
If you can produce at least one additional mana in step 4, this combo produces infinite mana.

Infinite creature ETB

Infinite creature LTB

Infinite mana lands you control can produce

Infinite storm count

Peregrine Drake

Man-o'-War

Panharmonicon

Cast Peregrine Drake by paying {4}{U}.
When Peregrine Drake enters the battlefield, it triggers itself twice due to Yarok.
Resolve one Peregrine Drake trigger, untapping five lands.
Activate those lands by tapping them to add at least {3}{U}.
Resolve the remaining Peregrine Drake trigger, untapping five lands.
Activate those lands by tapping them to add at least {3}{U}.
Cast Man-o'-War by paying {2}{U}.
When Man-o'-War enters the battlefield, it triggers itself twice due to Yarokg, returning itself and Peregrine Drake from the battlefield to your hand.
Repeat.
If you can produce at least one additional mana in step 4, this combo produces infinite mana.

Yarok, the Desecrated

Activate all mana-producing creatures you control by tapping them, adding at least {2}{U}.
Cast Man-o'-War by paying {2}{U}.
Man-o'-War enters the battlefield, triggering Intruder Alarm and Man-o'-War.
Resolve the Intruder Alarm's trigger, untapping all creatures you control.
Resolve the Man-o'-War's trigger, returning it to your hand.
Repeat.

Infinite mana creatures you control can produce

Infinite untap of creatures

Intruder Alarm

Cast Man-o'-War without paying its mana cost.
Man-o'-War enters the battlefield, triggering to return itself to your hand.
Repeat.

Aluren

Cast Man-o'-War by paying {2}{U}.
Volo triggers, creating a copy of the Man-o'-War spell.
The Man-o'-War copy enters, triggering itself.
Holding priority, activate Food Chain by exiling the Man-o'-War token, adding {U}{U}{U}{U} that can only be spent on creature spells.
Man-o'-War enters the battlefield, returning itself to your hand.
Repeat.

Infinite colored mana that can only be spent to cast creature spells

Return any number of creatures to their owners' hands

Volo, Guide to Monsters

Food Chain

Cast Petals of Insight by discarding Man-o'-War.
Containment Construct triggers, exiling Man-o'-War and allowing you to cast it from exile this turn.
Resolve Petals of Insight, putting the top three cards of your library on the bottom of your library, and returning Petals of Insight to your hand.
Cast Man-o'-War from exile by discarding Petals of Insight.
Containment Construct triggers, exiling Petals of Insight and allowing you to cast it from exile this turn.
Man-o'-War enters the battlefield, returning itself from the battlefield to your hand.
Cast Petals of Insight from exile by discarding Man-o'-War.
Repeat from step 2.

Infinite magecraft triggers

Infinite self-discard triggers

Dream Halls

Containment Construct

Petals of Insight

Cast Man-o'-War without paying its mana cost.
Man-o'-War enters the battlefield, targeting itself.
Molten Echoes triggers, creating a token copy of Man-o'-War.
Token copy of Man-o'-War enters the battlefield, returning original Man-o'-War to hand.
Resolve the original Man-o'-War triggers, fails to resolve due to having no legal targets.
Repeat.

Infinite creature tokens with haste

Molten Echoes

Cast _____ Goblin by paying {2}{R}.
_____ Goblin enters the battlefield, triggering its ability twice, getting two name stickers and adding at least eight {R}.
Activate Stonework Packbeast by paying {2}, adding {U}.
Cast Man-o'-War by paying {2}{U}.
Man-o'-War enters the battlefield, triggering its ability twice, returning itself and _____ Goblin from the battlefield to your hand and returning any stickers on them to your sticker sheets.
Repeat.

Infinite colored mana

_____ Goblin

Stonework Packbeast

Cast Petals of Insight by discarding Man-o'-War.
Conspiracy Theorist triggers, exiling Man-o'-War and allowing you to cast it from exile this turn.
Resolve Petals of Insight, putting the top three cards of your library on the bottom of your library, and returning Petals of Insight to your hand.
Cast Man-o'-War from exile by discarding Petals of Insight.
Conspiracy Theorist triggers, exiling Petals of Insight and allowing you to cast it from exile this turn.
Man-o'-War enters the battlefield, returning itself from the battlefield to your hand.
Cast Petals of Insight from exile by discarding Man-o'-War.
Repeat from step 2.

Conspiracy Theorist

At the beginning of your precombat main phase, There and Back Again triggers, creating a legendary 6/6 Smaug creature token, and causing you to sacrifice There and Back Again.
Cast Man-o'-War by paying {2}{U}.
Song of the Worldsoul triggers, creating a copy of the Smaug token.
Put a Smaug token into your graveyard due to the legend rule.
When the Smaug dies, it triggers, creating fourteen Treasure tokens.
When Man-o'-War enters the battlefield, it triggers, returning itself to your hand from the battlefield.
Activate three Treasure tokens by tapping and sacrificing them, adding {2}{U}.
Repeat from step 2.
Once you have infinite colored mana, you may use Song of the Worldsoul's trigger to target any other token you control instead.

Combos with "Man-o'-War"