Havenwood Sapling

{t}: Add {g}.
Whenever a green spell with 3 or more colors in
its mana cost is cast, Havenwood Sapling
becomes a 3/3 land creature that counts as a
Treefolk in addition to its other types. While a
land creature, all land creatures you control have Protection from Blue and Black and "{1}, {t}: Add
1 mana of any color." At the end of your next
turn, exile Havenwood Sapling then return it to
the battlefield under its owner's control.