Celebi, The Eternity Guide

Flying, Indestructible
Celebi, The Eternity Guide cannot attack or
block except during extra turns.
At the end of your turn, you may have Celebi
phase out until your next upkeep.
If Celebi would leave the battlefield, instead
return it to your hand and search your library for
an Instant or Sorcery card with mana value 5 or greater, put that card into your hand, then
shuffle your library.