Timestream Navigator by paying ({2} magic symbol) ({U} magic symbol) ({U} magic symbol) , tapping it and putting it from the battlefield onto the bottom of your library, causing you to take an extra turn after this one.
Activate
Isochron Scepter by paying ({2} magic symbol) and tapping it, casting a copy of
Entomb without paying its mana cost.
Resolve
Entomb, searching your library for
Timestream Navigator and putting it into your graveyard.
Cast
Timestream Navigator from your graveyard by paying ({1} magic symbol) ({U} magic symbol) .