All Summoner Icons have only their faces so people can tell who they are easier. If you see somebody from further away it's going to be harder to tell who it is than regular.
I messed around with your idea in Photoshop anyway, either way it's going to stand out and still appear ugly. I feel bad for telling them to make new summoner art for Lux, but please make another.
I think the art is amazing and has recently become WAY better, but this art is generally a bit too bright compared to the other art. Maybe try darkening it in some way will make it better.
Final Conclusion: Art is overall amazing, I'll give you that; but it just doesn't fit with all the other summoner icons. My thoughts are that editing this art to make a better summoner icon won't work, she generally has a big forehead and this just makes it stand out even more.
Keep up the good work.