You have a way to give Boros Reckoner lifelink.
You have a way to deal damage to Boros Reckoner.

Give Boros Reckoner lifelink.
Cast Boros Charm by paying , giving permanents you control indestructible until end of turn.
Deal damage to Boros Reckoner.
Boros Reckoner triggers, dealing that much damage to itself and causing you to gain that much life.
Repeat step 4 any number of times.

Pariah attached to Stuffy Doll.
You are the player chosen with Stuffy Doll.

Tap Stuffy Doll to deal one damage to yourself.
Start infinite mandatory triggers.

You control at least one creature.

Cast Ephemerate by paying , targeting any creature you control.
Holding priority, cast Dualcaster Mage by paying .
Dualcaster Mage enters the battlefield, creating a copy of Ephemerate targeting Dualcaster Mage.
Resolve the copy of Ephemerate, blinking Dualcaster Mage.
Repeat from step 3.

You control at least one creature.
You have enough mana to cast Sublime Epiphany

Cast Sublime Epiphany by paying its mana cost, targeting a creature you control.
Holding priority, cast Dualcaster Mage by paying .
When Dualcaster Mage enters the battlefield, it triggers, copying Sublime Epiphany, targeting Dualcaster Mage.
Resolve the copy of Sublime Epiphany, creating a token copy of Dualcaster Mage.
Repeat from step 3.

You may choose more of Sublime Epiphany's modes, if desired.

You control at least one creature.
You have enough mana to cast Rite of Replication

Cast Rite of Replication by paying its mana cost, targeting a creature you control.
Holding priority, cast Dualcaster Mage by paying .
When Dualcaster Mage enters the battlefield, it triggers, copying Rite of Replication, targeting Dualcaster Mage.
Resolve the copy of Rite of Replication, creating a token copy of Dualcaster Mage.
Repeat from step 3.

You have a way to give Brash Taunter lifelink.
Your life total is at least 51.

Give Brash Taunter lifelink.
Activate Aetherflux Reservoir by paying fifty life, dealing fifty damage to Brash Taunter.
Brash Taunter triggers, dealing fifty damage to an opponent and causing you to gain fifty life.
Repeat from step 2.

Cast Rite of Replication with kicker by paying , creating five token copies of Terror of the Peaks.
The five Terror of the Peaks tokens enter the battlefield, triggering the nontoken Terror of the Peaks five times and each Terror of the Peaks token four times.
Resolve all Terror of the Peaks triggers, dealing 125 damage divided among a maximum of 25 targets.

At the beginning of your combat phase, Xenagos triggers, giving Malignus +X/+X until end of turn, where X is Malignus's power.
Cast Chandra's Ignition by paying , causing Malignus to deal damage equal to its power to each other creature and each opponent.
Each opponent loses the game due to having zero or less life.

You control at least one creature.
You have enough mana to cast Quasiduplicate

Cast Quasiduplicate by paying its mana cost, targeting a creature you control.
Holding priority, cast Dualcaster Mage by paying .
When Dualcaster Mage enters the battlefield, it triggers, copying Quasiduplicate, targeting Dualcaster Mage.
Resolve the copy of Quasiduplicate, creating a token copy of Dualcaster Mage.
Repeat from step 3.

Cast Blasphemous Act by paying at most , dealing 13 damage to each creature and causing you to gain life equal to the damage dealt this way due to Soulfire Grand Master.

You have an instant or sorcery card in hand.

Cast any instant or sorcery spell.
Holding priority, cast Increasing Vengeance for its flashback cost by paying .
Sevinne triggers, creating a copy of Increasing Vengeance, targeting Increasing Vengeance.
Resolve the copy of Increasing Vengeance, creating a copy of Increasing Vengeance, targeting Increasing Vengeance.
Repeat step 4.

You control at least one creature.

Cast Momentary Blink by paying , targeting any creature you control.
Holding priority, cast Dualcaster Mage by paying .
Dualcaster Mage enters the battlefield, creating a copy of Momentary Blink targeting Dualcaster Mage.
Resolve the copy of Momentary Blink, blinking Dualcaster Mage.
Repeat from step 3.

Cast Chandra's Ignition by paying , causing Malignus to deal damage equal to three times its power to each other creature and each opponent.
Each opponent loses the game due to having zero or less life.

Cast Malignus by paying .
When Malignus enters the battlefield, Terror of the Peaks triggers, dealing an amount of damage equal to three times Malignus' power to an opponent.
The opponent loses the game due to having zero or less life.

Cast Necromantic Selection by paying .
Holding priority, cast Dualcaster Mage by paying .
When Dualcaster Mage enters the battlefield, it triggers, copying Necromantic Selection.
Resolve the copy of Necromantic Selection, destroying all creatures and returning Dualcaster Mage from your graveyard to the battlefield.
Repeat from step 3.

Cast Chandra's Ignition by paying , causing Malignus to deal damage equal to twice its power to each other creature and each opponent.
Each opponent loses the game due to having zero or less life.

Cast Malignus by paying .
When Malignus enters the battlefield, Terror of the Peaks triggers, dealing an amount of damage equal to twice Malignus' power to an opponent.
The opponent loses the game due to having zero or less life.

Cast Chandra's Ignition by paying , causing Malignus to deal damage equal to twice its power to each other creature and each opponent.
Each opponent loses the game due to having zero or less life.

You have the highest life total.
You control at least one additional creature.

Cast Hatred by paying and by paying life equal to the highest life total among your opponent, causing any other creature you control to get +X/+0 until end of turn, where X is the life paid this way.
Activate Jarad by paying and sacrificing the creature, causing each opponent to lose life equal to the creature's power.
Each opponent loses the game due to having zero or less life.

Cast Journey to Nowhere by paying .
Journey to Nowhere enters the battlefield, triggering its first ability, exiling itself.
Journey to Nowhere leaves the battlefield, triggering its second ability, returning itself from exile to the battlefield.
Repeat from step 2.

Cast Malignus by paying .
When Malignus enters the battlefield, Terror of the Peaks triggers, dealing an amount of damage equal to twice Malignus' power to an opponent.
The opponent loses the game due to having zero or less life.

Cast Chandra's Ignition by paying , causing Malignus to deal damage equal to twice its power to each other creature and each opponent.
Each opponent loses the game due to having zero or less life.

Cast Star of Extinction by paying , destroying a land and dealing 20 damage to each creature and each planeswalker, and causing you to gain life equal to the damage dealt this way due to Soulfire Grand Master.

Cast Malignus by paying .
When Malignus enters the battlefield, Terror of the Peaks triggers, dealing an amount of damage equal to twice Malignus' power to an opponent.
The opponent loses the game due to having zero or less life.

Soul Link attached to Boros Reckoner.
You have a way to give Boros Reckoner indestructible.
You have a way to deal damage to Boros Reckoner.

Give Boros Reckoner indestructible, and then deal damage to Boros Reckoner.
Boros Reckoner and Soul Link's second ability trigger.
Resolve the Soul Link trigger, causing you to gain that much life.
Resolve the Boros Reckoner trigger, dealing that much damage to itself.
Boros Reckoner and Soul Link's first and second abilities trigger.
Resolve both Soul Link triggers, causing you to gain life equal to twice the damage dealt.
Repeat from step 4.

Soul Link attached to Spitemare.
You have a way to give Spitemare indestructible.
You have a way to deal damage to Spitemare.

Give Spitemare indestructible, and then deal damage to Spitemare.
Spitemare and Soul Link's second ability trigger.
Resolve the Soul Link trigger, causing you to gain that much life.
Resolve the Spitemare trigger, dealing that much damage to itself.
Spitemare and Soul Link's first and second abilities trigger.
Resolve both Soul Link triggers, causing you to gain life equal to twice the damage dealt.
Repeat from step 4.

Cast Temporal Mastery by paying .
Riku's first ability triggers - choose not to pay.
Holding priority, cast Narset's Reversal by paying , targeting Temporal Mastery.
Riku's first ability triggers, causing you to pay to copy Narset's Reversal, with the copy targeting the original Narset's Reversal.
Resolve the copy of Narset's Reversal, copying the original Narset's Reversal targeting Temporal Mastery, and returning the original Narset's Reversal to your hand.
Resolve the copy of Narset's Reversal created in step 5, copying Temporal Mastery and returning the original Temporal Mastery to your hand.
Resolve Temporal Mastery, causing you to take an extra turn after this one.
Repeat each turn.

You may pay an additional to copy the extra turn spell, and only need to do this loop during your second extra turn.

Activate Chromatic Orrery's first ability by tapping it, adding .
Activate Emiel by paying , blinking Pestermite.
Pestermite enters the battlefield, untapping Chromatic Orrery.
Repeat.
Once you have infinite mana, you may instead activate Chromatic Orrery's second ability to draw infinite cards.