Deckard Cain was a Horadric scholar well versed in obscure lore and history of the arcane. Diablo is an action role-playing video game series (sometimes called hack and slash) developed by Blizzard Entertainment. It is made up of three core games: Diablo, Diablo II, and Diablo III.
Expansion games include the third-party published Diablo: Hellfire, which follows the first game, and Lord of Destruction, published by Blizzard and released after the second game. Reaper of Souls is the expansion for Diablo III.