Timestream Navigator + Flameshadow Conjuring + Riptide Laboratory

Timestream Navigator

Flameshadow Conjuring

Riptide Laboratory

How it works

1. Cast Timestream Navigator by paying 1.
2. If you don't have the city's blessing and control ten or more permanents, Timestream Navigator gives you the city's blessing.
3. When Timestream Navigator enters the battlefield, Flameshadow Conjuring triggers, causing you to pay to create a token copy of Timestream Navigator with haste.
4. If you don't have the city's blessing, the Timestream Navigator token gives you the city's blessing.
5. Activate Crystal Shard by paying 3 or and tapping it, returning the nontoken Timestream Navigator to your hand from the battlefield.
6. Activate the Timestream Navigator token by paying 2, tapping it and putting it on the bottom of your library from the battlefield, causing you to take an extra turn after this one.
7. Repeat each turn.