I made this Leyblood farming guide to help out players who want to farm Leyblood instead of buying them from the Auction House. I decided to search for places with high density of mobs which I can kill and drop [Leyblood]. I traveled around Broken Isles, and after a while I made a list of places.
Keep in mind! In Legion, several people can tag the same mob and still get loot. So, even if someone is already killing your mob, you can just help him and you can loot it too.
Killing Misthollow Hunters is the best way to farm Leyblood. Better geared players will probably have to wait for respawns because they will kill the mobs too fast. While waiting for respawns, you could go to the yellow marked location and kill the few packs of Moonlight Hunter that you find there.
The second place is also in Suramar. You will find a bunch of Thicket Hunter at the marked locations. I only recommend this place if the first one is already farmed by someone.
This place was the best farming place, unfortunately it got nerfed so now it's only good if you quickly need a few leyblood. There is a cave in Azurewing Repose where you will find a lot of Flashwyrm. You can pull all of them together and just AoE them down to quickly get 40-50 leyblood.
The respawn rate is really long, so that's why I only recommend this if you only need a few Leyblood. If you can't find anything in the cave then someone already killed them.