Hidden Grove

Hidden {0} (Rather than cast this card from your
hand, you may pay {0} and exile it. At the beginning
of your upkeep, add a hidden counter. As long as a
hidden counter is on this, it can be played from exile.)
Hidden Grove enters the battlefield with storage
counters equal to the number of hidden counters
it had.
{t}, Remove a storage counter from Hidden Grove:
Add {g}{g}.