Dryad of Ashfall

When Dryad of Ashfall enters the battlefield,
you may put a land card from your graveyard
on top of your library.
Sacrifice a Forest: Add X mana in any
combination of {r} and/or {g} where X is
the number of lands in your graveyard.
Retrace(You may cast this card from your graveyard
by discarding a land card in addition to paying its
other costs.)