Runes question!
I noticed that most guides keep recommending specific runes over and over again. I'm kind of confused because things like mana regen seals and health regen rune are never recommended even though they provide a lot a "gold". You'd think that some mana dependent champs would want this. Like for example an adc might decide that having more laning power from being able to cast spells more often will benefit them more than having a bit more armor.
So basically what I am asking is are these runes neglected because they aren't as good as I am thinking or just because people aren't bothering to think about them.