Cast Approach of the Second Sun by paying {6}{W}, causing you to gain seven life and put Approach of the Second Sun into your library seventh from the top.
Activate Scroll Rack by paying {1}, and tapping it, exiling seven cards from your hand, putting the top seven cards of your library into your hand, then putting the exiled cards on top of your library.
Cast Approach of the Second Sun by paying {6}{W}, causing you to win the game.

Win the game

Approach of the Second Sun

Scroll Rack

Activate Scroll Rack by paying {1} and tapping it, causing you to exile Medomai the Ageless from your hand and put the top card of your library into your hand, then put Medomai the Ageless from exile on top of your library.
Declare Arthur and at least one other creature as attackers.
Arthur triggers, causing you to reveal the top six cards of your library and put Medomai the Ageless onto the battlefield tapped and attacking.
Deal combat damage using Medomai the Ageless.
Medomai the Ageless triggers, causing you to take an extra turn after this one.
At the end of your combat phase, Arthur triggers, returning Medomai the Ageless from the battlefield to your hand.
Repeat each turn.

Infinite turns

Arthur, Marigold Knight

Medomai the Ageless

Tap Scroll Rack and pay {1} to activate it, putting Time Warp on top of your library.
Pass the turn.
On your next draw step, when you draw Time Warp, reveal it due to Kefnet's ability, making a copy that costs {2} less to cast.
Cast the copy for {1}{U}{U}, granting you an extra turn.

Skip your draw step

God-Eternal Kefnet

Time Warp

Tap Scroll Rack and pay {1} to activate it, putting Temporal Mastery on top of your library.
Pass the turn.
On your next draw step, when you draw Temporal Mastery, reveal it due to Kefnet's ability, making a copy that costs {2} less to cast.
Cast the copy for {3}{U}{U}, granting you an extra turn.

Temporal Mastery

Tap Scroll Rack and pay {1} to activate it, putting Nexus of Fate on top of your library.
Pass the turn.
On your next draw step, when you draw Nexus of Fate, reveal it due to Kefnet's ability, making a copy that costs {2} less to cast.
Cast the copy for {3}{U}{U}, granting you an extra turn.

Nexus of Fate

Tap Scroll Rack and pay {1} to activate it, putting Temporal Manipulation on top of your library.
Pass the turn.
On your next draw step, when you draw Temporal Manipulation, reveal it due to Kefnet's ability, making a copy that costs {2} less to cast.
Cast the copy for {1}{U}{U}, granting you an extra turn.

Temporal Manipulation

Tap Scroll Rack and pay {1} to activate it, putting Expropriate on top of your library.
Pass the turn.
On your next draw step, when you draw Expropriate, reveal it due to Kefnet's ability, making a copy that costs {2} less to cast.
Cast the copy for {5}{U}{U}, granting you an extra turn.

Expropriate

Tap Scroll Rack and pay {1} to activate it, putting Karn's Temporal Sundering on top of your library.
Pass the turn.
On your next draw step, when you draw Karn's Temporal Sundering, reveal it due to Kefnet's ability, making a copy that costs {2} less to cast.
Cast the copy for {2}{U}{U}, granting you an extra turn and returning up to one nonland permanent to its owner's hand.

Karn's Temporal Sundering

Tap Scroll Rack and pay {1} to activate it, putting Capture of Jingzhou on top of your library.
Pass the turn.
On your next draw step, when you draw Capture of Jingzhou, reveal it due to Kefnet's ability, making a copy that costs {2} less to cast.
Cast the copy for {1}{U}{U}, granting you an extra turn.

Capture of Jingzhou

Tap Scroll Rack and pay {1} to activate it, putting Beacon of Tomorrows on top of your library.
Pass the turn.
On your next draw step, when you draw Beacon of Tomorrows, reveal it due to Kefnet's ability, making a copy that costs {2} less to cast.
Cast the copy for {4}{U}{U}, granting you an extra turn.

Beacon of Tomorrows

Tap Scroll Rack and pay {1} to activate it, putting Time Stretch on top of your library.
Pass the turn.
On your next draw step, when you draw Time Stretch, reveal it due to Kefnet's ability, making a copy that costs {2} less to cast.
Cast the copy for {6}{U}{U}, granting you two extra turns.

Time Stretch

Tap Scroll Rack and pay {1} to activate it, putting Walk the Aeons on top of your library.
Pass the turn.
On your next draw step, when you draw Walk the Aeons, reveal it due to Kefnet's ability, making a copy that costs {2} less to cast.
Cast the copy for {2}{U}{U}, granting you an extra turn.

Walk the Aeons

Tap Scroll Rack and pay {1} to activate it, putting Temporal Trespass on top of your library.
Pass the turn.
On your next draw step, when you draw Temporal Trespass, reveal it due to Kefnet's ability, making a copy that costs {2} less to cast.
Cast the copy for {6}{U}{U}{U}, granting you an extra turn.

Temporal Trespass

Tap Scroll Rack and pay {1} to activate it, putting Part the Waterveil on top of your library.
Pass the turn.
On your next draw step, when you draw Part the Waterveil, reveal it due to Kefnet's ability, making a copy that costs {2} less to cast.
Cast the copy for {2}{U}{U}, granting you an extra turn.

Part the Waterveil

Activate Scroll Rack by paying {1} and tapping it, exiling Felidar Guardian from your hand face down, then putting the top card of your library into your hand and putting Felidar Guardian onto the top of your library.
Declare Arthur and another creature as attackers, triggering Arthur, looking at the top six cards of your library and putting Felidar Guardian onto the battlefield tapped and attacking. 
When Felidar Guardian enters, it and Preston trigger.
Resolve the Felidar Guardian trigger, blinking another permanent you control.
Resolve the Preston trigger, creating a token copy of Felidar Guardian that is a 0/1 Illusion.
When the Felidar Guardian token enters the battlefield, it triggers, blinking the nontoken Felidar Guardian.
Repeat from step 3.

Infinite LTB

Infinite ETB

Infinite creature tokens

Infinite landfall triggers

Infinite blinking of permanents you control

Infinite mana lands you control that enter the battlefield untapped can produce

Exile any number of nonland permanents

Preston, the Vanisher

Felidar Guardian

Activate Scroll Rack by paying {1} and tapping it, exiling Worldfire from your hand face down, then causing you to draw one card and put Worldfire on top of your library.
Cast any sorcery spell from your hand by paying its mana cost.
Possibility Storm and Guttersnipe trigger.
Resolve the Possibility Storm trigger, exiling the sorcery spell, then exiling Worldfire from the top of your library and casting it without paying its mana cost.
Guttersnipe triggers, dealing 2 damage to each opponent.
Resolve Worldfire,  exiling all permanents, all cards in all hands and graveyards, and setting each player's life total to one.
Resolve the Guttersnipe trigger from step 3, dealing 2 damage to each opponent.
Each opponent loses the game due to having less than zero life.

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