New Runes - Unleashing The Fury (Gameplay Idea)

Hello Everyone!

The idea is pretty simple, so I'll keep it short. There are many runes and a lot of them are really useful/very nice. I noticed that in the shop there is everything from armor pen to bonus gold per 10 seconds, and there is even energy regeneration capacity runes! How about we get "Fury Generation" runes for marks or quints or something of the sort, that allow for X% bonus to fury generation. A lot of champions could make use of it like Shyvanna prolonging her transformation duration, and ability to reach that initial transformation too. Renekton could throw out modified abilities more often, and that might help with his damage output/sustain! I'm not sure how exactly balance it would be, since it might be one of those things that requires you to have too high of a value of bonus rage gain to feel good about it and really notice it, and if it is that high, then it would just really break the game and be too unbalanced. I'm not sure if this is the case or not, but what do you guys think?