If I am correct the rune 'Aery' is supposed to proc on incoming damage on enemies, right? (ignite as an exception). However, when I wanted to try Aery on Sivir, as I thought it would be fun to proc Aery with Ricochet, it did not proc when Ricochet bounced to enemies. I find this to be odd as it is damage from a champion's spell.
I have sent a bug report about this before, but I did not receive any reply whether this is how it supposed to work. In my eyes this is not how it is supposed to work, because Jhins Q also bounces and procs Aery. ;)