In Bastion Stairs, left wing there is an arena with level 33 champion non-aggressive spawns all along the top. For some reason these are incredibly weak and can be solo 'd by a single level 24. If your AOE based you may be able to solo 3-4 at such a low level.
I've heard this may have been recently nerfed though in the last 2 days to where these NPCs can only be attackable in certain stages of the PQ. Have not had a chance to test this yet.