Blizzard Entertainment built its own internal generative AI tool, called Blizzard Diffusion, to help designers and artists generate concept art during game development. Unlike publicly available AI tools, it was trained only on Blizzard's own art assets. The tool's existence was revealed in May 2023 following an internal company email that described it as "a major evolution" in how Blizzard builds games.

Blizzard Diffusion is a customized version of Stable Diffusion trained exclusively on Blizzard-owned artwork to avoid copyright complications that come with tools trained on scraped internet content. Chief Design Officer Allen Adham's internal email, reported by The New York Times in May 2023, described the tool and outlined future ambitions including AI-assisted voice cloning, procedurally assisted level design, and autonomous in-game NPCs (non-player characters). Blizzard prohibits use of third-party generative AI tools on company intellectual property. VP Andrew Guerrero framed the tool as removing repetitive tasks so artists can focus on creative work. Despite this framing, a patent for AI-generated artwork surfaced around the same time and drew backlash from the artist community. Individual Blizzard game teams retain the ability to opt out — the Overwatch and World of Warcraft teams have both publicly stated they are not using generative AI for player-facing content.