Timestream Navigator + Echocasting Symposium

Prerequisites

You control nine or more permanents and/or have the city's blessing.

Steps

1. Cast Echocasting Symposium by paying {4}{U}{U}, creating a token copy of Timestream Navigator and exiling Echocasting Symposium.
2. If you don't have the city's blessing, the Timestream Navigators will give you the city's blessing.
3. Activate the oldest Timestream Navigator by paying {2}{U}{U}, tapping it and putting it from the battlefield onto the bottom of your library, causing you to take an extra turn after this one.
4. Move to your next turn. At the beginning of your precombat main phase, Echocasting Symposium's paradigm ability triggers, causing you to cast a copy of it from exile. Resolve the copy, creating a token copy of Timestream Navigator.
5. Repeat from step 3.