I doubt there's any gem costume going to be released soon. The valianite costume ticket is a selector, and that probably means any future releases will be valianite onwards. So it might be hard to put a valianite reward for buying the remaining gem costumes.
Aside from disabling skill effects, it would be nice to have an option that disables the map effects like snow, etc. Granted I have a mid-end phone, even setting the graphics to medium or low results in a fps drop.