Freehold Character Leveling is currently the fastest way possible to level your World of Warcraft Character from 110 to 120.
You will be invited by a fully geared Demon Hunter Twink who will solo the Battle for Azeroth instance: Freehold for you. All you have to do is stand back, enjoy the tremendous amount of experience gain and loot all the corpses once it’s safe for you.
This method is as fast as 15 minutes per level up, all the way to 120.
Typically it takes 3 instance runs per level, taking 5 minutes each. This means your character can be leveled from 110 to 120 in around 2 hours and a half, while you’re more or less not doing anything yourself other than looting corpses.