House in a Forest

When House in a Forest enters the battlefield, target creature gets -3/-3.
{g}{g}{t}: Target creature gets -2/-2 until end of turn.
{g}{g}{t}: Target creature gets +2/+2 until end of turn.
If a spell or ability causes you to discard this card, you may pay {g}{g}. If you do, every opponent sacrefices and discards a card.