Nari, WinterSage Shaman

{1}{g}{w}{t}: Search your library for a basic forest or plains card and put it onto the battlefield tapped. Then shuffle your library. Nari doesn't untap during your next untap step.
Formidable - {8}{g}{g}, {t}: Tap all lands each opponent controls. They don't untap during their controllers' next untap steps. Then sacrifice Nari. Activate this ability only if creatures you control have total power 8 or greater.