It is hard for me to kill those things. There is a lot. Thats why I need xp... any other idea?
I suggest 2 things. Optimize your build and skills for attack damage, rapture chance/ damage and xp gain.
Go to the last stage of the ice world and try not to die in the boss stage? (more like a world where you lose hp gradually and fight of enemies), when you come out of that dimension you get some good xp and there is a chance to get some of the best perfected gear available in the game. At the highest difficulty you can get lvl10 equipment. Now it's only a matter of time before you achieve near absolute power.