Sorcery, 4W (5)
Rare
Each player chooses from the lands he or she controls a land of each basic land type, then sacrifices the rest.
"The earth shook, the sky rained fire, and it seemed the world was ending."
—Benalish refugee
Illus. Greg Staples

10/4/2004: If a land counts as multiple basic land types, you can choose it for either or for both of those land types.
8/15/2010: You sacrifice all lands other than the chosen ones. Since you can only choose lands with basic land types, any non-basic lands that don't have a basic land type (even if they have some other land type, as in the case of Cloudpost) are necessarily going to be sacrificed.
Legal in Vintage (Type 1)
Legal in Legacy (Type 1.5)
Legal in Classic (MTGO)
Legal in Commander