Whomping Willow

{t}: Add one {g} to your mana pool
{2}{g}: Whomping Willow becomes a 3/3 creature
with Defender until end of turn. It is still a land
"Not to mention the damage you've inflicted on a
Whomping Willow that's been on these grounds since
before you were born!"
"Honestly Professor, I think it did more damage
to us."