River Song + Timestream Navigator

River Song

Timestream Navigator

How it works

1. During your upkeep, activate Timestream Navigator by paying 2, tapping it and putting it on the bottom of your library, causing you to take an extra turn after this one.
2. Move to your draw step, drawing Timestream Navigator from the bottom of your library due to River Song.
3. Cast Timestream Navigator by paying 1.
4. Repeat each turn.

This clever loop lets you take infinite turns by endlessly recycling your own threats, enabled by River Song's unique rules text altering how you draw cards. Normally, tucking Timestream Navigator to the bottom of your library would make it difficult to access again, but River Song ensures you draw it immediately during your draw step. Once you recast Timestream Navigator—assuming you have the city's blessing to satisfy its activation requirement—you simply repeat the process every single turn to lock the game down completely.