Echocasting Symposium + Eternal Witness + Walk the Aeons

Echocasting Symposium

Eternal Witness

Walk the Aeons

How it works

1. Cast Walk the Aeons by paying its mana cost, causing you to take an extra turn after this one.
2. Move to your next turn. At the beginning of your precombat main phase, Echocasting Symposium's paradigm ability triggers, causing you to cast a copy of it from exile.
3. Resolve the copy, creating a token copy of Eternal Witness
4. When the Eternal Witness token enters, it triggers, returning Walk the Aeons from your graveyard to your hand.
5. Repeat.