Crumbling Landscape

When Crumbling Landscape enters the battlefield, sacrifice it unless you exile a land you control.
{t}: Place a crumble counter on Crumbling
Landscape. Then for each crumble counter on Crumbling Landscape, add one mana of any color
that the exiled land could produce. Then, if Crumbling Landscape has 6 or more
crumble counters on it, sacrifice it.