Walk the Aeons, Call to Mind, Mystic Retrieval, and Swarm Intelligence

Prerequisites

• Walk the Aeons in hand
• Call to Mind in hand
• Mystic Retrieval in the graveyard
• Swarm Intelligence on the battlefield
• on each odd-numbered turn, with at most available each even-numbered turn available

Steps

1. Cast Walk the Aeons by paying
2. Swarm Intelligence triggers, copying Walk the Aeons
3. Resolve both Walk the Aeonss, causing you to take two extra turns after this one
4. Move to your next turn
5. Cast etiher Mystic Retrieval or Call to Mind by paying its mana cost, targeting either Call to Mind or Mystic Retrieval in your graveyard
6. Swarm Intelligence triggers, copying Call to Mind or Mystic Retrieval, targeting Walk the Aeons
7. Resolve both Call to Minds or Mystic Retrievals, returning Walk the Aeons and either Call to Mind or Mystic Retrieval from your graveyard to your hand
8. Move to your next turn
9. Repeat

Results

• Infinite turns
• Instant/Sorcery with "Return Instant/Sorcery from GY to hand"