Cast Dance of Many by paying {U}{U}.
When Dance of Many enters the battlefield, its first ability triggers, creating a token copy of Felidar Guardian.
When the Felidar Guardian token enters the battlefield, it triggers, blinking Dance of Many.
Dance of Many's first and second abilities trigger.
Resolve the second trigger, exiling the Felidar Guardian token.
Resolve the first trigger, creating a token copy of Felidar Guardian.
Repeat from step 3.

Infinite creature LTB

Infinite creature ETB

Dance of Many

Felidar Guardian

Cast Astral Dragon by paying {6}{U}{U}.
Astral Dragon enters the battlefield, creating two token copies of Dance of Many that are 3/3 Dragons in addition to their other types.
The Dance of Many tokens enter the battlefield, triggering their first abilities.
Resolve one Dance of Many trigger, creating a token copy of Astral Dragon.
Repeat from step 2 any number of times, creating an additional Dance of Many trigger on the stack each loop.
Once you have infinite Dance of Many triggers, resolve them all, creating infinite copies of all nontoken creatures.
As you are resolving the triggers, you may also target Astral Dragon any number of times to create infinite copies of all noncreature permanents that are 3/3 Dragon creatures in addition to their other types.
At the beginning of your upkeep, pay {U}{U} for each Dance of Many or sacrifice that permanent and exile its associated creature token.

Infinite copies of any nontoken creatures

Infinite creature copies of all noncreature permanents

Infinite creature tokens

Astral Dragon

Cast Lion's Eye Diamond from your graveyard by paying {0}.
Activate Lion's Eye Diamond by sacrificing it and discarding your hand, adding {U}{U}{U}.
Cast Dance of Many from your graveyard by paying {U}{U}.
When Dance of Many enters the battlefield, its first ability triggers, creating a token copy of Muldrotha.
Put the nontoken Muldrotha into your graveyard due to the legend rule.
Cast Lion's Eye Diamond from your graveyard by paying {0}.
Activate Lion's Eye Diamond by sacrificing it and discarding your hand, adding {B}{B}{B}.
Cast Animate Dead from your graveyard by paying {1}{B}, returning Muldrotha from your graveyard to the battlefield with Animate Dead attached to it.
Put the token Muldrotha into your graveyard due to the legend rule.
When the Muldrotha token dies, Dance of Many's third ability triggers, causing you to sacrifice Dance of Many.
Repeat.
Once you have infinite mana, you may cast any other permanent cards in your graveyard that are not solely enchantments and/or artifacts.

Cast all nonartifact, nonenchantment permanent cards in your graveyard

Infinite colored mana

Infinite death triggers

Infinite creature sacrifice triggers

Infinite storm count

Muldrotha, the Gravetide

Lion's Eye Diamond

Animate Dead

Cast Lion's Eye Diamond from your graveyard by paying {0}.
Activate Lion's Eye Diamond by sacrificing it and discarding your hand, adding {U}{U}{U}.
Cast Dance of Many from your graveyard by paying {U}{U}.
When Dance of Many enters the battlefield, its first ability triggers, creating a token copy of Muldrotha.
Put the nontoken Muldrotha into your graveyard due to the legend rule.
Cast Lion's Eye Diamond from your graveyard by paying {0}.
Activate Lion's Eye Diamond by sacrificing it and discarding your hand, adding {B}{B}{B}.
Cast Necromancy from your graveyard by paying {2}{B}, returning Muldrotha from your graveyard to the battlefield with Necromancy attached to it.
Put the token Muldrotha into your graveyard due to the legend rule.
When the Muldrotha token dies, Dance of Many's third ability triggers, causing you to sacrifice Dance of Many.
Repeat.
Once you have infinite mana, you may cast any other permanent cards in your graveyard that are not solely enchantments and/or artifacts.

Necromancy

Cast Dance of Many, targeting Leonin Relic-Warder.
When Dance of Many enters the battlefield, it creates a token copy of Leonin Relic-Warder.
The token enters, exiling Dance of the Many.
Dance of Many leaves the battlefield, triggering to exile the token.
The token triggers, returning Dance of Many to the battlefield.
Repeat steps 2-5.

Leonin Relic-Warder

Cast Lion's Eye Diamond from your graveyard by paying {0}.
Activate Lion's Eye Diamond by sacrificing it and discarding your hand, adding {U}{U}{U}.
Cast Dance of Many from your graveyard by paying {U}{U}.
When Dance of Many enters the battlefield, its first ability triggers, creating a token copy of Muldrotha.
Put the nontoken Muldrotha into your graveyard due to the legend rule.
Cast Lion's Eye Diamond from your graveyard by paying {0}.
Activate Lion's Eye Diamond by sacrificing it and discarding your hand, adding {B}{B}{B}.
Cast Dance of the Dead from your graveyard by paying {1}{B}, returning Muldrotha from your graveyard to the battlefield with Dance of the Dead attached to it.
Put the token Muldrotha into your graveyard due to the legend rule.
When the Muldrotha token dies, Dance of Many's third ability triggers, causing you to sacrifice Dance of Many.
Repeat.
Once you have infinite mana, you may cast any other permanent cards in your graveyard that are not solely enchantments and/or artifacts.

Dance of the Dead

Cast Dance of Many by paying {U}{U}.
When Dance of Many enters the battlefield, its first ability triggers, creating a token copy of Mirror-Mad Phantasm.
Activate the Mirror-Mad Phantasm token's ability by paying {1}{U}, causing you to shuffle the token into your library and mill all cards from your library.

Infinite self-mill

Mirror-Mad Phantasm

Cast Dance of Many by paying {U}{U}.
Dance of Many enters the battlefield, creating a token copy of Magnanimous Magistrate.
Activate Altar of Dementia by sacrificing Dance of Many.
Dance of Many, Magnanimous Magistrate, and the token Magnanimous Magistrate trigger.
Resolve the nontoken Magnanimous Magistrate trigger, declining to act.
Resolve the token Magnanimous Magistrate trigger, removing two reprieve counters from it and returning Dance of Many from your graveyard to the battlefield.
Dance of Many enters the battlefield, creating a token copy of Magnanimous Magistrate.
Resolve the Dance of Many trigger, exiling the first Magnanimous Magistrate token.
Repeat from step 3 any number of times.
Resolve all Altar of Dementia abilities, milling any number of players any amount of cards.
You may sacrifice and return any number of creatures with mana value 3 or less in your graveyard any number of times.

Infinite blinking of some creatures and some creature cards in graveyard and in library

Infinite mill

Magnanimous Magistrate

Opalescence

Altar of Dementia

Cast Dance of Many by paying {U}{U}.
Dance of Many enters the battlefield, creating a token copy of Moorland Rescuer.
Activate Altar of Dementia by sacrificing the Moorland Rescuer token.
The Moorland Rescuer token dies, triggering itself and Dance of Many.
Resolve Dance of Many's trigger, sacrificing it.
Dance of Many leaves the battlefield, exiling nothing.
Activate Altar of Dementia by sacrificing Archon of Falling Stars.
Archon of Falling Stars dies, returning Dance of Many to the battlefield.
Dance of Many enters the battlefield, creating another token copy of Moorland Rescuer.
Let one Altar of Dementia trigger resolve, causing a player to mill four cards.
Let the Moorland Rescuer token's trigger from step 4 resolve, returning Archon of Falling Stars to the battlefield.
Let the remaining Altar of Dementia trigger resolve, causing the targeted player to mill four cards.
Repeat from step 2.

Combos with "Dance of Many"