idea for a 4th mini offensive runes giving on hit

along side adaptive force, a 4th option that gave 6 on hit that's doubled at level 9. and maybe have it convert 10cdr into on hit as well at level 9

or could do 9 flat and convert 10 cdr into 11 on hit total 20 on hit. there's a lot of ways to meet cdr nowadays and attackspeed heavy champs don't necessarily need more than say 20%