River Song + Conjurer's Bauble + Prototype Portal + Time Walk

River Song

Conjurer's Bauble

Prototype Portal

Time Walk

How it works

1. Activate Prototype Portal by paying 1 and tapping it, creating a token copy of Conjurer's Bauble.
2. Cast Time Walk by paying its mana cost, causing you to take an extra turn after this one.
3. Activate the Conjurer's Bauble token by tapping and sacrificing it, putting Time Walk onto the bottom of your library from your graveyard, and then causing you to draw Time Walk from the bottom of your library due to River Song.
4. Repeat each turn.