New Levelling Technique - Can Be Significantly Faster Than All Other Methods, High RNG, Time-Sensitive (Patreon)

Previously back in Warlords Of Draenor, there was a public if lesser known levelling technique which involved using cross-realm add-ons to repeatedly kill rare spawns whc typically award a lot of experience. The method only attracted limited interest because levelling via other methods at the time was trivial. Then cross-realm add-ons were nerfed, making them de facto useless for this purpose, essentially eliminating the method. 

However, I've discovered a workaround for farming rare spawns, and because everything else was nerfed it is one of, if not the most powerful levelling method currently. 

Create a number of class trials on low pop realms. Level your levelling character to 10. Now form a group on custom group finder with your class trial and have both class trial and levelling character join. This will send your levelling character into the low pop class trial realm-just leave the group to return to the original realm.

You'll find that on most low pop realms during off-peak periods that rare spawns are up more often than not, it is very satisfying being able to kill a rare on one realm, switch to another, and then kill it again. 

There is no need to limit yourself to one realm, you can create up to 4 class trials per week, and a maximum of 8 overall. 

Sophisticated players typically use add-ons to find rare spawns: personally I've never found that necessary, I just run around the spawn locations listed for rare spawns on that zone indicated by wowhead. 

This method does not have to be restricted to rare spawns. It can be used to effectively increase the respawn times of normal mobs-very useful when you get a large cluster of mobs in a region you want to farm which don't respawn quickly.

Used correctly at the right times this method is faster than anything else I've discovered. The main drawback is that it works much better at antisocial hours, is somewhat RNG (if someone is running through a zone methodically many rares will be dead), and can glitch out in certain zones when using just the one account.

EDIT: important! When killing rares make sure your high level character is in another part of the zone. If the high level character is close to the low level character the low level will receive almost no xp for any kill.