This clever setup transforms a modest sacrifice outlet into a complete library-emptying engine by turning a single land search into a closed loop of token generation and fuel. You kick things off using Perilous Forays to sacrifice a creature and fetch a land, which enters the battlefield tapped until Amulet of Vigor steps in to immediately untap it for use. Meanwhile, Down in the Valley's second chapter provides the crucial payoff by continuously spawning a fresh Elf token whenever that land arrives, giving you the exact fodder needed to feed Perilous Forays over and over again.