Slay the Spire is a roguelike deckbuilding game and this genre is fairly new with the first game in this genre called Dream Quest came out in 2014. Since the genre is so new there are not many tools that can help in the creation of games in the genre. Slay the Spire offers an extensive modding API which lets users create new content for the game. This would require the designer to have both programming knowledge and API knowledge which takes a lot of time to learn. This is why Design science as a methodology was chosen to create a UI to make it easier for designers without the required knowledge to still be able to create content for the game. A user study was then conducted to evaluate the usability of the UI. Experiments were also used to test the artifact to make sure content is created correctly.