Cast Seasons Past by paying ({4} magic symbol) ({G} magic symbol) ({G} magic symbol) , returning Walk the Aeons, Mystical Tutor, and any number of cards with different mana costs to your hand and putting Seasons Past on the bottom of your library.
Cast Mystical Tutor by paying ({U} magic symbol) , putting Seasons Past on top of your library.
Cast Walk the Aeons by paying ({4} magic symbol) ({U} magic symbol) ({U} magic symbol) , granting you an extra turn.
In the draw step of your next extra turn, draw Seasons Past.