River Song + Conjurer's Bauble + Prototype Portal + Capture of Jingzhou

River Song

Conjurer's Bauble

Prototype Portal

Capture of Jingzhou

How it works

1. Activate Prototype Portal by paying 1 and tapping it, creating a token copy of Conjurer's Bauble.
2. Cast Capture of Jingzhou 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 Capture of Jingzhou onto the bottom of your library from your graveyard, and then causing you to draw Capture of Jingzhou from the bottom of your library due to River Song.
4. Repeat each turn.