Seasons Past
Sorcery
Return any number of cards with different converted mana costs from your graveyard to your hand. Put Seasons Past on the bottom of its owner's library.
The seeds of new life take root in the soil of old.
Illustrated by
Shadows over Innistrad Promos#226sMythicEnglishLegality
Rulings
Apr 8, 2016
The phrase “different converted mana costs” compares the mana costs of cards in your graveyard to one another, not to Seasons Past. You may return a card with a converted mana cost of 6.
Apr 8, 2016
If a card in your graveyard has 
in its mana cost, X is considered to be 0.
Apr 8, 2016
A card with no mana cost, such as a land, has a converted mana cost of 0.
Apr 8, 2016
You choose which cards to return as Seasons Past resolves, not as you cast it.