The Shrine of Klothys

Indestructible
Foretell your destiny —You can look at the top four cards of your library at any time.
Whenever enchanted creature deals combat
damage to a player, you may pay {g/u}{u/r}{r/g}. If
you do, take an extra turn after this one. After that turn the next turn can't be an extra turn.
Enchant a creature {2}