You target two of your opponent's lands. On resolution, they return to the top of your opponent's library. Your opponent is now A) Down two mana AND B) Missing two draw steps.
The trick is to play it very, very early, and hopefully either in multiples or with similar cards like Fallow Earth, Temporal Spring, Memory Lapse, etc... Of course, you have to wear a cup when you play that sort of deck, but we all must make some sacrifices...