Return Land from Graveyard to Battlefield
When playing World Shaper with the new land cards, such as Song-Mad Treachery/Song-Mad Ruins. Should World Shaper return Song-Mad Ruins from the graveyard to the battlefield. It's ability reads "When World Shaper dies return all land cards from the graveyard to the battlefield tapped". Song-Mad Ruins is a land card, it can be played from the graveyard as a land using the Ancient Greenwarden ability.
From rulings: "Ancient Greenwarden allows you to play a modal double-faced card’s land face, but not a nonland face."
So there is currently a bug of Ancient Greenwarden, it allows to play the other face.
If you can CHOOSE cards to play from the GY or library, you can choose which side to play like with Ancient Greenwarden. However in the case of Worldshaper, since it says "all land cards" and there's no choice to be made, it only considers the front face of the card. Song-Mad Ruins is not a land card, even though it's back face is a land. It's a Sorcery in all zones except the stack and battlefield.
MDFC have the characteristics of their front face in all zones except the stack and battlefield.