Timestream Navigator + Riptide Laboratory + Archmage of Echoes

Prerequisites

• You have the city's blessing, and/or control (at least) eight permanents

Steps

1. 1Cast Timestream Navigator by paying .
2. 2Archmage of Echoes triggers, copying the Timestream Navigator spell.
3. 3Resolve both Timestream Navigator spells.
4. 4If you don't have the city's blessing, either the Timestream Navigator token or the nontoken Timestream Navigator gives you the city's blessing.
5. 5During your next turn, activate Riptide Laboratory's second ability by paying and tapping it, returning the nontoken Timestream Navigator to your hand from the battlefield.
6. 6Activate the ability of the Timestream Navigator token by paying , tapping it and putting on the bottom of your library, causing you to take an extra turn after that one.
7. 7Repeat.

Effects

• Infinite turns
• Lock