Manaflow band needs a nerf

This is not true tho. It just gives back some mana and make one cast free.

You also have to justify it with numbers if you want anyone to take you seriously.

Why does it need a nerf? What sort of nerf do you feel will be effective enough to weaken it, but not so strong as to make it a useless rune?

So remove energy and give champs with energy Mana instead, give Mana to Katarina, give Mana to gnar, ...