Timestream Navigator does not have summoning sickness.
Rancor attached to any other creature except Timestream Navigator.
({2} magic symbol) ({U} magic symbol) ({U} magic symbol) on your first turn, with ({2} magic symbol) ({G} magic symbol) ({U} magic symbol) ({U} magic symbol) available on each extra turn available.
Steps
Activate Timestream Navigator by paying ({2} magic symbol) ({U} magic symbol) ({U} magic symbol) , tapping it and putting it onto the bottom of your library, causing you to take an extra turn after this one.
At the beginning of your end step, Enigmatic Incarnation triggers, causing you to sacrifice Rancor and then search your library for Timestream Navigator and put it onto the battlefield.
Rancor triggers, returning itself from your graveyard to your hand.
Move to your next turn.
Cast Rancor by paying ({G} magic symbol) , attaching it to any other creature you control.