Nest Of The Firebringers

Nest Of The Firebringers enters the battlefield
tapped unless you reveal the top card of your
library.
{t}: Untap target Forest or Mountain.
{x}{r/g}{r/g}, {t}: Exile the top X cards of your library.
You may cast those cards as long as they remain
exiled. If you cast a creature exiled this way, put
two +1/+1 counters onto target creature.