Sunastian Windcaller

{t}: Add two mana in any combination of colors
to your mana pool. If this mana is spent on a
creature spell, that creature enters the battlefield
with an additional +1/+1 counter. If this mana
is spent on an instant or sorcery, that spell can't
be countered.
{3}{g}{g}, {t}: Add X mana in any combination of
colors to your mana pool, where X is the number
of creatures on the battlefield.