Sylvan Arches

{t}: Add {g}{g} to your Mana pool. None of you creatures can attack this turn. Use this ability only during your turn.
{2},{t}: Until end of turn, all your green creatures gain the ability: "{t}: add {g} to your
Mana pool". If four or more creatures are tapped this way during your turn, you may untap up to four creatures. These creatures gain Vigilance until end of turn.