Planar Contraction

Planar Contraction does not untap during
your untap step.
Sacrifice a land, {t}: Add {u}{r}{g} to your
mana pool.
{u/r}{r/g}{g/u}: Untap Planar Contraction.
While Planar Contraction is untapped, your
opponents may not play land if they control
more land than you.