Timestream Navigator, and Phyrexian Devourer

Prerequisites

• Timestream Navigator on the battlefield
• Phyrexian Devourer on the battlefield
• You have the city's blessing
• each turn available

Steps

1. During your upkeep step, activate Phyrexian Devourer by exiling the top card of your library
2. Repeat step 1 until you have an empty library
3. Resolve all Phyrexian Devourer abilities, eventually causing you to sacrifice it
4. Activate Timestream Navigator by paying , tapping it and putting it on the bottom of your library, causing you to take an extra turn after this one
5. Move to your draw step, drawing Timestream Navigator from your library
6. Cast Timestream Navigator by paying
7. Move to your next turn
8. During your upkeep step, activate Timestream Navigator by paying , tapping it and putting it on the bottom of your library, causing you to take an extra turn after this one
9. Repeat from step 5

Results

• Infinite turns