There are permanents on the battlefield that enter the battlefield untapped and produce at least ({3} magic symbol) ({R} magic symbol) ({R} magic symbol) .
Cast Mythos of Illuna targeting anything but Archaeomancer, holding priority, and then cast Radiate targeting Mythos of Illuna.
When Radiate resolves you will have Mythos copies targeting every targetable permanent (except what the original Mythos card is targeting).
When each of the copies resolve, target Radiate in your graveyard with the new Archaeomancer token's ability and return Radiate to your hand.
Before the original Mythos of Illuna card resolves, cast Radiate again targeting Mythos by spending mana from the tokens you just created.
Repeat this process, effectively doubling the number of copies created, allowing you to return Radiate and another card with two Archaeomancer triggers.
Repeat.
Results
Infinite copies of all targetable permanents.
Infinite storm count.
Return any number of instant and sorcery cards (except Mythos of Illuna) from your graveyard to your hand any number of times.