You have a number of cards in hand that is above your maximum hand size, one of which must be a land card.

Proceed to your cleanup step, and discard a land and any other card(s) as needed down to your maximum hand size.
The Gitrog Monster triggers, causing you to mill two cards and return a land from your graveyard to your hand.
Repeat, as you will still be over your maximum hand size and will be required to discard again.

You have a way to draw a card.
Your deck size is greater than your opponents' combined life totals.

Draw a card.
Queza triggers, causing target opponent to lose 1 life and you to gain 1 life.
Drogskol Reaver triggers, causing you to draw a card.
Repeat from step 2.

You have the highest life total or are tied for the highest life total.

Activate Vizkopa Guildmage's second ability by paying , causing each opponent to lose life whenever you gain life this turn.
Cast Revenge by paying , doubling your life total and causing target opponent to lose half their life, rounded up.
Vizkopa Guildmage triggers, causing each opponent to lose life equal to the life you gained.
Each opponent loses the game due to having zero or less life.

An opponent has lost life this turn.

Cast Murderous Redcap by paying .
Murderous Redcap enters, triggering itself, dealing damage to itself equal to its power.
Murderous Redcap dies, triggering its persist ability, returning it to the battlefield with a -1/-1 counter and at least one +1/+1 counter from Gev.
The -1/-1 counter and a +1/+1 counter are both removed as a state-based action.
Repeat from step 2.

Cast Murderous Redcap by paying , which enters with a +1/+1 counter on it due to Grumgully.
When Murderous Redcap enters the battlefield, it triggers, dealing an amount of damage to itself equal to its power.
Murderous Redcap dies as a state-based action due to having 0 toughness.
Murderous Redcap's persist ability triggers, returning it from your graveyard to the battlefield without a -1/-1 counter on it due to Grumgully.
Repeat from step 2.

Your library size is at least twenty.

Cast Body of Research by paying , creating a 0/0 Fractal creature token, then putting a +1/+1 counter on it for each card in your library.
Simic Ascendancy triggers, putting that many growth counters on itself.
At the beginning of your next upkeep, Simic Ascendancy triggers, causing you to win the game.

Cast Murderous Redcap by paying , which enters with a +1/+1 counter on it due to Rhythm of the Wild.
When Murderous Redcap enters the battlefield, it triggers, dealing an amount of damage to itself equal to its power.
Murderous Redcap dies as a state-based action due to having 0 toughness.
Murderous Redcap's persist ability triggers, returning it from your graveyard to the battlefield without a -1/-1 counter on it due to Rhythm of the Wild.
Repeat from step 2.

At the beginning of your end step, Soulherder's second ability triggers, blinking Azor.
Soulherder's first ability triggers, putting a +1/+1 counter on itself.
Azor enters the battlefield, preventing opponents from casting instants or sorceries during their next turn.
Repeat during each of your turns.

All permanents do not have summoning sickness.
An opponent is unable to block and kill Brago and Aurelia.

Declare Brago and Aurelia as attackers, attacking an opponent unable to block and kill them.
Aurelia triggers, untapping all creatures you control and causing you to get an additional combat phase after this phase.
Deal combat damage with Brago and Aurelia.
Brago triggers, blinking Aurelia.
Repeat each combat phase.

Cast Moritte by paying , choosing to have it enter the battlefield as a copy of Bladewing.
Put Bladewing from the battlefield into your graveyard due to the legend rule.
Moritte's enter-the-battlefield ability triggers, returning Bladewing from your graveyard to the battlefield.
Put Bladewing from the battlefield into your graveyard due to the legend rule.
Bladewing's enter-the-battlefield ability triggers, returning it from your graveyard to the battlefield.
Repeat from step 4.

A way to draw a card or gain life.

Draw a card or gain life.
Whenever you draw a card you gain 1 life.
Whenever you gain life, draw a card.
Repeat.

You have a way to give Shalai and Hallar lifelink.
You have a way to put a +1/+1 counter on a creature you control.

Put a +1/+1 counter on a creature you control.
Shalai and Hallar triggers, dealing 1 damage to an opponent and causing you to gain one life.
Trelasarra triggers, putting a +1/+1 counter on itself and causing you to scry 1.
Repeat from step 2.

Cast an instant or sorcery spell, or wait for an opponent to cast one.
Holding priority, cast Expansion by paying , targeting the spell.
Activate Rootha by paying and returning it to your hand, copying Expansion, with the copy targeting the original Expansion.
Resolve the copy of Expansion, copying Expansion, targeting the original Expansion.
Repeat step 4.

You control an additional nontoken creature that does not have summoning sickness.
An opponent is unable to block creatures you control.

Declare the additional creature as an attacker, attacking an opponent unable to block it.
When the creature is unblocked, activate Medomai's ninjitsu ability by paying and returning the creature to your hand, putting Medomai onto the battlefield tapped and attacking.
Deal combat damage with Medomai, triggering its ability, causing you to take an extra turn after this one.
Before the combat phase ends, activate the creature card in your hand's ninjutsu ability by paying and returning Medomai from the battlefield to your hand, putting the creature onto the battlefield tapped and attacking.
Repeat each turn.

Declare Lord Xander as an attacker, triggering its second ability, causing the defending player to mill half their library, rounded up.
Activate Consuming Aberration by tapping it, causing the opponent to mill cards equal to the cards in opponents' graveyards, milling the remainder of their library.

Faeburrow Elder does not have summoning sickness.
You control a black and a red permanent.

Activate Faeburrow Elder by tapping it, adding .
Activate High Alert by paying , untapping Faeburrow Elder.
Repeat.

Master of Cruelties does not have summoning sickness.
You have a creature card in hand with power one or greater.
An opponent is unable to block Master of Cruelties.

Declare Master of Cruelties as an attacker, attacking an opponent unable to block it.
When Master of Cruelties isn't blocked, its ability triggers.
Holding priority, activate any creature card with power one or greater in your hand's ninjutsu ability by paying and returning Master of Cruelties from the battlefield to your hand, putting the creature card onto the battlefield tapped and attacking.
Resolve the Master of Cruelties trigger, causing the blocking opponent's life total to become one.
Deal combat damage with the attacking creature, causing the opponent's life total to become zero or less.
The opponent loses the game due to having zero or less life.

Cast Murderous Redcap by paying .
When Murderous Redcap enters the battlefield, it and Good-Fortune Unicorn trigger.
Resolve the Good-Fortune Unicorn trigger, putting a +1/+1 counter on Murderous Redcap.
Resolve the Murderous Redcap trigger, dealing an amount of damage to itself equal to its power.
Murderous Redcap dies as a state-based action due to having 0 toughness.
Murderous Redcap's persist ability triggers, returning it from your graveyard to the battlefield with a -1/-1 counter on it.
Repeat from step 2.

Cast Moritte of the Frost by paying , choosing to have it enter the battlefield as a copy of Havi.
Put Moritte of the Frost into your graveyard due to the legend rule.
When Moritte of the Frost dies, it and Havi trigger.
Resolve the Havi trigger, returning Moritte of the Frost from your graveyard to the battlefield as a copy of Havi.
Repeat from step 2.
Resolve all Moritte of the Frost triggers from step 3, returning all legendary creature card(s) with mana value 5 or less from your graveyard to the battlefield.

At least one opponent has lost life this turn.

Activate Bartolomé del Presidio by sacrificing the creature with persist.
The persist ability triggers, returning that creature to the battlefield with a -1/-1 counter on it, as well as a +1/+1 counter due to Gev.
The +1/+1 and -1/-1 counters on that creature are removed as a state-based action.
Resolve the ability from step 1, putting a +1/+1 counter on Bartolomé del Presidio.
Repeat.

You control at least two other creatures that do not have summoning sickness.
Etrata does not have summoning sickness.
An opponent controls at least three nontoken creatures.

Cast Echoing Equation by paying , causing each other creature you control to become a nonlegendary copy of Etrata.
Deal combat damage to an opponent with Etrata and two other creatures you control.
Etrata and the two creatures trigger.
Resolve the first Etrata trigger, exiling a nontoken creature the opponent controls with a hit counter on it, and shuffle Etrata into your library.
Repeat step 4 one additional time.
Resolve the last Etrata trigger, exiling a nontoken creature the opponent controls with a hit counter on it, shuffle Etrata into your library, and cause the opponent to lose the game.

Cast Murderous Redcap by paying , which enters with a +1/+1 counter on it due to Master Biomancer.
When Murderous Redcap enters the battlefield, it triggers, dealing an amount of damage to itself equal to its power.
Murderous Redcap dies as a state-based action due to having 0 toughness.
Murderous Redcap's persist ability triggers, returning it from your graveyard to the battlefield without a -1/-1 counter on it due to Master Biomancer.
Repeat from step 2.

Cast Murderous Redcap by paying .
When Murderous Redcap enters the battlefield, it and Juniper Order Ranger trigger.
Resolve the Juniper Order Ranger trigger, putting a +1/+1 counter on it and Murderous Redcap.
Resolve the Murderous Redcap trigger, dealing an amount of damage to itself equal to its power.
Murderous Redcap dies as a state-based action due to having 0 toughness.
Murderous Redcap's persist ability triggers, returning it from your graveyard to the battlefield with a -1/-1 counter on it.
Repeat from step 2.