A friend told me carries like magebane and chronos should get runed axe to farm better. But I don't get how that works because past level 10 or so lanes are too dangerous and the only things going on are team fights. Did he mean that you should use the runed axe to jungle (since it's like the only safe place past level 10)?
There are a variety of ways to have runed axe be effective in terms of farming. Magebane and Chronos both have a good escape mechanism that allows them to move from lane to lane for farming. The jungle (especially stacked creeps) are a great way to use the runed axe. With a supportive team who wards often, it should become pretty safe to farm lanes.
do you need to have a life to be able to live somewhere?
The Runed Cleaver is good to farm, but not always picked up.
If you can pick it up around the 20 min mark go for it, else it's mayby better to go other items. This all depence how the game is going for your team and youreself.