Cast Doppelgang by paying ({15} magic symbol) ({G} magic symbol) ({U} magic symbol) , creating five token copies of Eternal Witness and of the four mana-producing permanents.
When the Eternal Witness tokens enter the battlefield, they trigger, returning Doppelgang and up to four other instant or sorcery cards from your graveyard to your hand.
Activate seventeen of the mana-producing permanent tokens by tapping them, adding at least ({15} magic symbol) ({G} magic symbol) ({U} magic symbol) .
Repeat.
Once you have infinite tokens and mana, you may instead target any other permanents using Doppelgang.
Results
Infinite copies of any permanent on the battlefield.
Infinite creature tokens.
Infinite ETB.
Infinite landfall triggers.
Infinite magecraft triggers.
Infinite mana permanents can produce.
Infinite storm count.
Return all cards from your graveyard to your hand.
Infinite casts of instants and sorceries in your hand and graveyard.