I am developing an app that pulls data from the API. The app will be free to download, however I plan on providing custom – purely cosmetic – themes that users can choose. I want to make those themes available for a small fee. I am aware of the regulation that the API must not be used in commercial contexts, however I am unsure if my idea breaks this rule or if it would be allowed, considering it's only an optional and only cosmetic feature, not in any way blocking out access to the data.
Im taking an accurate guess and telling you that you cannot make profit off of anything you want to do regarding Bungie and Destiny. Hopefully a Bungie employee or someone with more knowledge than I know of can confirm or tell you otherwise. Best of luck!
EDIT: This should answer your question
[quote]You may not use the Bungie.net API for commercial purposes unless you obtain Bungie’s prior written permission. If your use of the Bungie.net API generates any revenue, your use is commercial. If you are in doubt about whether your application is commercial, here are a few common examples of commercial use that may provide you some guidance:
Users are charged a fee for your product or service that includes some sort of integration using the Bungie.net APIs;
You sell services to Bungie.net users and use the APIs to bring users' Bungie.net content into your service;
Your site uses API Data to drive traffic and generate ad revenue.