An Option to purchase item instead chest
The problem with rng chest is that not everyone like it when comes to paying a chest thats not guaranteed for them unless they buy them all.
The suggestion i could give is that :
Allow players to buy Event Skins, Emotes, Sprays etc in separate manner similar to buying non-even skin.
But you can make the chest cheaper than the single purchasing system so that
One, players either can spend their stuff only for favourite champions
Two, players who choose the chest that became cheaper save money than the one who chose single item.