Been shit kicking around on my new character playthrough. Just doing dungeons and equipment farms, most of caelid, linuria, dragonbarrow, etc.
Didn't do any major bosses, just did the smaller forts and dungeons. I powerleveled a lot in fort farrow or whatever the name is near the big dragon. Those harpies and bats are really easy with a collosol weapon, every hit staggers them and a three hit combo knocks them flat on the ground. It's an easy 10k+ runes per clear and super fast. Annoying that the harpies can always one shot you if they land their head attack but it's pretty easy to dodge. Definitely my favorite spot before I unlock the approach ledge.