Overwatch heroes icons in mine app

Hi!

I want to create a free standalone application that will contain information about the synergy between heroes, about callouts that good to say while the game. The purpose is to share my game knowledge. I need icons of heroes while development. Is it possible from a licence point of view to use screenshots from the game for that purpose?

If you know any source of free icons with overwatch heroes I would appreciate if you share it with me.

Thanks.