I don't always use mana potions...

You forgot Yorick Mori. Everyone forgets Yorick Mori.

Those are pity potions for people who don't get blue buff.

I kinda use them everytime I play a support , an ADC that can abuse his high damage abilities , or a bully mage (Karma , Diana after 6).

Buffing mana potions can lead to serious abuse of it by some champions: and maybe.

Think about the fact that for a champ that can use his abilities to heal , mana pots have the potential to out sustain health pots , leading to a 10 health pots champ. I don't want to mention that some of them practically can trade some of their pots to an ally ;)

Edit: champs with shields or high poke are other potential abusers too.Also I forgot about and his E. Damn that fish!!! @@