Echocasting Symposium + Eternal Witness + Time Warp

Echocasting Symposium

Eternal Witness

Time Warp

How it works

1. Cast Time Warp 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 Time Warp from your graveyard to your hand.
5. Repeat.