I miss this old classic time :( So sad that they remove this kind of rune system. This will give you in games enhancements or to provide some stats superiority against other players. You could build a pure damage rune or scaling damage, tank runes, magic pen runes and anything you would like to apply to your playstyle.
I really remember experimenting and also testing my new runes at PVP, I try to figure out what is the most effective but sadly after a few season they remove it and the runes was exchange by blue essence later on. It is kind a sad that I will no longer gain some Influence points where I can buy champions and many more.
Tell me what are your insight about RIOT changes at the game of League of Legends.
Have a nice day.