THE BINDING OF ISAAC: FOUR SOULS – EDMUND BOOSTER PACK – To celebrate the sixth anniversary of Four Souls, Edmund McMillen and Maestro Media joined forces to craft three exciting new booster packs for The Binding of Isaac: Four Souls. Each booster pack is packed to the brim with 15 cards that will make exciting new additions to any players existing Four Souls collection. The Edmund Booster Pack features a thrilling roster of cards inspired by Edmunds other games.