Unnatural Photosynthesis

Choose one-
•{t}: Add {g}{g}{g} per land you control
•{t}: Add {b}{b}{b} per land you control
For each land you control, put one Wither
counter on each land. When any Wither counter reaches thirteen, transform each land you control into a 0/0 Dead Sapling that deals one damage
to the controller at the beginning of each upkeep.