Rozšírenie už klasickej LCG hry Call of Cthulhu. Hra je v anglickom jazyku a tento jazyk je pre hru potrebný,  popis preto uvádzame v angličtine: The Key and the Gate, the fourth deluxe expansion for Call of Cthulhu: The Card Game and introduces 165 cards (three copies each of fifty-five individual cards) that explore the mysteries of Yog-Sothoth and the eerie, fictional word of H.P. Lovecraft. With nearly two-thirds of its cards serving to develop the identity of Yog-Sothoth and its mysteries and minions, The Key and the Gate is an excellent expansion for fans of the Ancient One and players who like the faction's strengths in discard, recursion, and control rooted in arcane knowledge. Meanwhile, it also introduces Yithians to the Living Card Game format, bolsters Sorcerers with new Spells, and bestows powerful support cards upon each of the other factions, as well as characters with the new Fated keyword.