When Shivan Wumpus enters the battlefield, first the active player gets the option to sacrifice a land. If he or she declines, the next player in turn order gets the option. If a player elects to sacrifice a land, Shivan Wumpus is put on top of its owner’s library, but then all remaining players still get the option. If all players decline, then nothing happens and Shivan Wumpus stays on the battlefield.

This is the timeshifted version of Argothian Wurm.