Echocasting Symposium + Time Walk + Shipwreck Dowser

Echocasting Symposium

Time Walk

Shipwreck Dowser

How it works

1. Cast Time Walk 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 Shipwreck Dowser
4. When the Shipwreck Dowser token enters, it triggers, returning Time Walk from your graveyard to your hand.
5. Repeat.