Making Mana a More Fun Stat
Champion diversity is hard to balance out. We get it. But items? Some items just clearly are underwhelming and buffing them would do so much for the game. My favorite example is
.
Stats +80 attack damage +10% life steal +10% cooldown reduction
Passive Unique Passive: Your basic attacks restore mana equal to between 2% and 8% of the physical damage dealt, based on your missing mana.
The passive better be damn strong to compete with
, but it's not. So many champions could love this item but quite frankly the mana regen isn't strong enough to make up for the weaker life steal and shield. Just a few short examples of champions would could love this item:

Unconventional, but it could add for some very interesting builds if we made this better. How about we do this to the passive:
Passive Unique Passive: Your basic attacks restore mana equal to between 5% of the physical damage dealt, based on your **total **mana.
This could also encourage players to build
which is a fantastic item and only a few champs build it.
Mana is one of those stats that is just a slight annoyance early on and basically means nothing late game. By giving players a reason to build mana and a few items that utilize it better, I'll bet we see more diversity in champion select and champion builds.
TLDR; Make mana more fun by strengthening mana AD and regen items.