Plant a Sapling // Fully-Grown Treefolk

Search your library for a basic land card, reveal it, put it into your hand, then shuffle this spell into its owner's library transformed. (For playtesting purposes, put it into its sleeve upside down.)
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(You can't cast this face unless it's been transformed by the front face.)
Fully-Grown Treefolk's power and toughness are each equal to the number of lands you control.