The Mirari Conjecture with two lore counters on it).
Mana Needed
({8} magic symbol) ({U} magic symbol) ({U} magic symbol) at most each turn available.
Steps
At the beginning of your precombat main phase.
The Mirari Conjecture triggers, putting a lore counter on it. Its third chapter ability then triggers, copying instant and sorcery spells you cast this turn.
Cast
Time Stretch by paying ({8} magic symbol) ({U} magic symbol) ({U} magic symbol) .
The Mirari Conjecture triggers, copying
Time Stretch.
Resolve both
Time Stretches, causing you to get four extra turns after this one.
Move to your first extra turn.
Activate
Conduit of Worlds by tapping it, targeting
The Mirari Conjecture and causing you to pay ({4} magic symbol) ({U} magic symbol) to cast it from your graveyard.
The Mirari Conjecture enters with a lore counter on it, triggering its first chapter ability, returning an instant card from your graveyard to your hand.
Move to your second extra turn. At the beginning of your precombat main phase.
The Mirari Conjecture triggers, putting a lore counter on it. Its second chapter ability then triggers, returning
Time Stretch from your graveyard to your hand.
Move to your third extra turn and repeat from step 1.
Notes
During the first extra turn, you will not be able to cast other spells, but you can during the remaining turns as desired.