Nissa, Vastwood Seer

When Nissa, Vastwood Seer enters the battlefield,
you may search your library for a basic Forest
card, reveal it, put it into your hand, then shuffle.
—Whenever a land enters the battlefield under
your control, if you control seven or more lands,
exile Nissa, then return her to the battlefield transformed under her owner's control.
This is the Sacred Forest Meadow. It's my secret place!
I feel... This place will be very important for both of us someday.