Caverns of Eternity

{0}, Exile a land you control: Put a loyalty
counter on Caverns of Eternity.
{t}: Until your next turn, Caverns of Eternity
becomes a legendary planeswalker with
+1: You may play an additional land this turn
-1: Add 2 mana of any one color
-6: Search your library for up to 5 basic lands,
put them onto the battlefield, then shuffle your library.