There have been server specific rune groups for most of the servers (that had them obviously) at one time or another.
The only ones I’m still aware of are pretty dead though.
There are limits but they’re pretty high and aren’t as much the issue as suggested runes change pretty drastically with rarity.
What’s good for O4 is not good for O6 etc etc. That’s the main reason most rune groups have been server specific.
Too much chatter about what you’re doing with Cyan alienates the people it’s there to help and confuses them about what stats are good and what stats are obsolete in their current environment.
That being said, anyone who just honestly needs questions answered is welcome.
Please be specific though when asking or answering questions about higher rarity heroes.