An idea for the new rune system

I have an Idea, how about if we have option to chose runes during the game. what if at lets say level 5,10,15 we get to choose from 2-3 option for stat upgrade based on what you need in that game at that time. for example on zed you get to choose +20 lethality, or 50 more dmg or +3 percentage armor shred. you can chose which one is better for you. Each rune would be champion specific so for example the lv 10 rune would be different for each champion unless the champion is very similar. at level 18 you unlock a special rune upgrade to one thing a buff for a weakness or making a strength stronger, for example on garen if you q you get slow immunity or you could chose lets say flat 1000 true dmg on ult, in some situations when the enemy team has lot of slows it doest matter if garen has lot of dmg if he cant reach players and etc. it could give league players greater amount of customization and reward for getting ahead .These rune option also could change builds, and give players answers for certain in game situations .