From a gameplay mechanics perspective, it's great.
Could you provide a complete list of possible buffs that can be applied to skills and perks in this way?
To be honest, I didn't keep a complete list because initially, I was just attaching runes and focusing on the buffs I saw on creatures (battle rage and bear resilience). But then I also became interested in city buffs. Here's what I have:
I found and verified all of this in this list:
