Start Location: Auridon 49.9, 41.8
Get the quest Through the Ashes from Captain Landare.
Do all steps untill you get to Stop the Ritual
This will lead you to an Abandoned Mine. Right before the end of the abandoned mine there is two level 12 daedra mages in front of a fire portal. They both gives 122 xp. Kill the mages but DO NOT click the portal, because this will complete the quest and you will not be able to reset them.
To reset the mages you just run back down the way you came past the torch before the two flame astronach and they will respawn.
I did this on my night blade at lvl 10 and did 15k xp per hour
Vintev on the left cast fire and Demis on the right summons pets.
Other players can actually complete this quest if you are to close to the portal, so if you see another player run towards the reset area so the quest doesnt complete.
If the quest gets completed you can simply abandon the quest but you will have to do the beginning of the quest again...
I hope that you find this helpfull!