This case study investigates if the AI text-to-image generator Midjourney can generate visual game character idea images for Dota 2 that meet the game’s art guidelines. The author defined the term “visual game character ideas” as the idea images at the early stage of visual character design process to help artists get inspiration. To achieve this, an experiment was designed and conducted where three new Dota 2 heroes’ backgrounds were developed by the author, and 32 images per hero were generated with Midjourney bot. These 96 images were evaluated to examine Midjourney’s performance based on seven aspects: accurate content, readability and identifiability, value gradient, value patterning, the number of colors, areas of rest and detail, and directionality. “YES” was given to each criterion if they meet the requirement. The value of this case study is to present the strength and weakness of the text-to-image generators for visual character design ideas, which can potentially show game artists when and how to use them in visual character design process. The result suggested that Midjourney could be used to generate visual character design ideas for Dota 2 unstably, and this instability was mainly caused by its identified flaw: content accuracy. Furthermore, it performed better for non-color-related aspects, while the performance for color-related items was significantly worse than others.