Okay, if you go left in Throne of Tides and kill the first 2 Tainted Sentry the smaller Unstable Corruptions keep respawning every few seconds giving constant 500-600ish xp while in a group of 5. Rinse and repeat for lots of levelling!!
I recommend carrying someone to heal with you as there is a stacking debuff which hurts quite a bit but definitely doable without a tank.
Will post images and stuff when I do it again.
They respawn really quick so may be rather quick way to level.
Screenshots