A solution to true damage runes: Reverse-Adaptive damage
It's evident that runes which deal true damage have been a problem. They first had to nerf Press the Attack, and now Conqeuror has become an issue on meta fighters. My suggestion to fix this is reverse-adaptive damage; that is, bonus and/or converted damage would be converted to magic damage if you're AD and vice-versa.
This would fix the issue of there being no counter building at all, while still being an edge in damage. Someone building defense would have to make a choice between the type of damage they want to mitigate, rather than not having that choice at all.
The reason Conqueror is an issue goes back to the tank item "update" (all-around nerfs). Since they were adjusted to have less HP and more of their specific defensive stat, true damage is more powerful than it should be. Conqueror would've been fine in a game state prior to that update, but now it's not.