Neverwinter Nights 2: Storm of Zehir is an expansion pack for the role-playing video game Neverwinter Nights 2, developed by Obsidian Entertainment and published by Atari. It was released in late 2008 in North America, Europe, and Australia. Like previous entries in the Neverwinter Nights series, Storm of Zehir is based on the paper and pencil fantasy role-playing game Dungeons & Dragons, and uses the game's 3.5 edition ruleset.