Manaflow Band seems a little out of the line:
Every 60 seconds, your next ability used has its mana or energy cost refunded, and restores 8% of your missing mana or energy.
The problems:
Can't keep track of the cooldown
Too OP for champions that have little Mana problems, not enough power for champions that have a lot of mana problems.
My Suggestion:
Every 90 seconds, your next ability used has its mana or energy cost refunded, the refund value is increased by 1% per 10 Missing Mana. Casting Abilities will reduce the cooldown by 5 seconds.
Why does it solves the problem:
Champions with high mana costs will have more significant refund
Champions that need to spam skills will have more frequent refund
Champions that don't use their abilities very often won't get free infinite Mana anymore
