Cast Biovisionary by paying {1}{G}{U}.
Holding priority, cast Double Major by paying {G}{U}, targeting the Biovisionary spell.
Riku's first ability triggers, causing you to pay {U}{R} to copy Double Major, targeting the Biovisionary spell.
Resolve both Double Majors, copying the Biovisionary spell twice.
Resolve all Biovisionary spells.
The nontoken Biovisionary enters the battlefield, triggering Riku's second ability, causing you to pay {G}{U} to create a token copy of Biovisionary.
At the beginning of your end step, each Biovisionary triggers.
Resolve the first Biovisionary trigger, causing you to win the game.

Win the game

Riku of Two Reflections

Biovisionary

Double Major

Cast Palinchron for {5}{U}{U}.
Palinchron enters the battlefield, triggering itself and Riku.
Resolve the Palinchron trigger, untapping up to seven lands that can tap to produce at least {3}{U}{U}{U}{G}.
Activate the seven lands by tapping them, adding at least {3}{U}{U}{U}{G}.
Resolve the Riku trigger, costing you {U}{G} to create a copy of Palinchron.
The Palinchron copy enters the battlefield, untapping up to seven lands that can tap to produce at least {3}{U}{U}{U}{G}.
Activate the seven lands by tapping them, adding at least {3}{U}{U}{G}.
Activate the non-token Palinchron by paying {2}{U}{U}, returning it to your hand.
Repeat.

Infinite creature tokens

Infinite ETB

Infinite LTB

Infinite mana lands you control can produce

Infinite storm count

Palinchron

Cast Time Warp by paying {3}{U}{U}.
Riku's first ability triggers - choose not to pay.
Holding priority, cast Narset's Reversal by paying {U}{U}, targeting Time Warp.
Riku's first ability triggers, causing you to pay {U}{R} 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 Time Warp, and returning the original Narset's Reversal to your hand.
Resolve the copy of Narset's Reversal created in step 5, copying Time Warp and returning the original Time Warp to your hand.
Resolve Time Warp, causing you to take an extra turn after this one.
Repeat each turn.

Infinite turns

Narset's Reversal

Time Warp

Cast Astral Dragon by paying {6}{U}{U}.
When Astral Dragon enters the battlefield, it and Riku of Two Reflections' second ability trigger.
Resolve the Astral Dragon trigger, creating four token copies of Parallel Lives that are 3/3 Dragon creatures in addition to their other types.
Resolve the Riku of Two Reflections' second ability trigger, causing you to pay {G}{U} to create a total of 32 Astral Dragon tokens with haste.
When the Astral Dragon tokens enter the battlefield, they trigger, creating an extremely large number of Parallel Lives tokens that are 3/3 Dragon creatures in addition to their other types.

Near-infinite creature tokens

Near-infinite ETB

Astral Dragon

Parallel Lives

Cast Astral Dragon by paying {6}{U}{U}.
When Astral Dragon enters the battlefield, it and Riku of Two Reflections' second ability trigger.
Resolve the Astral Dragon trigger, creating four token copies of Doubling Season that are 3/3 Dragon creatures in addition to their other types.
Resolve the Riku of Two Reflections' second ability trigger, causing you to pay {G}{U} to create a total of 32 Astral Dragon tokens with haste.
When the Astral Dragon tokens enter the battlefield, they trigger, creating an extremely large number of Doubling Season tokens that are 3/3 Dragon creatures in addition to their other types.

Doubling Season

Cast Worldgorger Dragon by paying {3}{R}{R}{R}.
Worldgorger Dragon enters the battlefield, triggering its first ability and Riku's second ability.
Holding priority, activate any number of permanents by tapping them, adding at least {1}{G}{U}.
Resolve the Riku trigger, causing you to pay {G}{U} to create a token copy of Worldgorger Dragon.
The token Worldgorger Dragon enters the battlefield, triggering its first ability, exiling all other permanents you control.
The nontoken Worldgorger Dragon leaves the battlefield, triggering its second ability, returning nothing from exile to the battlefield.
Resolve the Worldgorger Dragon trigger from step 2, exiling the token Worldgorger Dragon.
The token Worldgorger Dragon leaves the battlefield, triggering its second ability, returning all permanents exiled with it to the battlefield.
Repeat from step 2.

Infinite blinking of permanents you control

Infinite mana permanents you control can produce

Worldgorger Dragon

Cast Astral Dragon by paying {6}{U}{U}.
When Astral Dragon enters the battlefield, it and Riku of Two Reflections' second ability trigger.
Resolve the Astral Dragon trigger, creating four token copies of Primal Vigor that are 3/3 Dragon creatures in addition to their other types.
Resolve the Riku of Two Reflections' second ability trigger, causing you to pay {G}{U} to create a total of 32 Astral Dragon tokens with haste.
When the Astral Dragon tokens enter the battlefield, they trigger, creating an extremely large number of Primal Vigor tokens that are 3/3 Dragon creatures in addition to their other types.

Primal Vigor

Cast Finale of Devastation by paying {3}{G}{G}.
Holding priority, activate Riku by paying {U}{R}, copying Finale of Devastation.
Resolve the copy of Finale of Devastation, searching your library and/or graveyard for Biovisionary and putting it onto the battlefield.
Riku triggers, causing you to pay {U}{G} to create a token copy of Biovisionary.
Resolve the original Finale of Devastation, searching your library and/or graveyard for Mirror Image and putting it onto the battlefield as a copy of Biovisionary.
Riku triggers, causing you to pay {U}{G} to create a token copy of Mirror Image, which enters the battlefield as a copy of Biovisionary.
At the beginning of your end step, each Biovisionary triggers.
Resolve the first Biovisionary trigger, causing you to win the game.

Finale of Devastation

Mirror Image

Cast Astral Dragon by paying {6}{U}{U}.
When Astral Dragon enters the battlefield, it and Riku of Two Reflections' second ability trigger.
Resolve the Astral Dragon trigger, creating four token copies of Anointed Procession that are 3/3 Dragon creatures in addition to their other types.
Resolve the Riku of Two Reflections' second ability trigger, causing you to pay {G}{U} to create a total of 32 Astral Dragon tokens with haste.
When the Astral Dragon tokens enter the battlefield, they trigger, creating an extremely large number of Anointed Procession tokens that are 3/3 Dragon creatures in addition to their other types.

Combos with "Riku of Two Reflections"