An issue with how mana on ADCs are dealt with.
Why is reducing the mana cost a thing on champs AD casters, ADC and even bruisers? It just makes manamune, an item that is bought by the few champs in the pool, even less appealing.
New Yorick doesn't buy manamune anymore and now Jayce doesn't build it anymore since you lowered the mana cost on his E. Jayce now rushes ghostblade so manamune loses yet another customer. Ez, Varus, and Urgot are the only ones now that bother with manamune. I'm sure there are others but from the top of my head thats the three i can think of.
Even Reaver seems less appealing. Why does Lucians dash mana cost go down in level? It just further encourages Lucian to go armor pen items since he doesn't have to worry about mana cost.

... the dream.
still has a broken kit with that blink+damage E. No reason for him to have such a low cooldown so for him to be able to use that infinately when its up with
. He is the king of positioning, burst damage, and dps in the adc world which is why he's always a competitive pick. Lucian has a more balanced kit.
needs mana early if you spam Q being irresponsible with it but as you level she doesn't need any mana buffing. By then there's no need to get
some more even though the only people I see really moaning about him are those who want him reverted because they were season 5 mains.