in Luskan town area, you can fight the same monster over and over again ( just walk around and they'll respawn ). that's how I can get the level cap fast.
the portal in Kluth place where it wil spawn imps. is also a good place to gain experience points.
One of the floor of host tower ( where it got multiple portal that will spawn imps like creature ) is a good place too.
you just have to be patient though.
