A Diablo artbook advert in the German magazine Gamestar may have just confirmed the upcoming Diablo IV.

Roughly translated the ad reads, The Art of Diablo will feature "over 500 artworks from Diablo, Diablo II, Diablo III, and Diablo IV.

There's always the possibility this could be a typo, but the timing is a little too convenient. Adding weight to this are previous statements from a Blizzard community manager noting there were "many plans for Diablo across multiple projects which we'll be revealing over the course of the coming year."

The book is set to release the day after Blizzcon, the most obvious event at which to reveal the upcoming title.

That there's a direct sequel to Diablo III in the works is a surprise to almost no one – although the news will be a relief to many after the outcry over Diablo: Immortal, a mobile game that was announced at last year's Blizzcon.

Between Blizzard's recent controversy and the rumoured list of game reveals, this year's Blizzcon is shaping up to be a must-see event.