| 4/8/2016 |
The phrase "different mana values" compares the mana costs of cards in your graveyard to one another, not to Seasons Past. You may return a card with a mana value of 6. |
| 4/8/2016 |
If a card in your graveyard has  in its mana cost, X is considered to be 0. |
| 4/8/2016 |
A card with no mana cost, such as a land, has a mana value of 0. |
| 4/8/2016 |
You choose which cards to return as Seasons Past resolves, not as you cast it. |
|