I think EK’s should be at least lvl 300 to block the bosses there, mages can be lower 150~200 can do it with full energy protection and mana shield (I recomend being lvl 200 at least but you can make access lower), paladins are better after lvl 250 to go in this quest, the creatures there aren’t strong but it has a lot of them in the way to the bosses.
To make this quest in lower lvls you need to know exactly where you going because you can waste too much supply and end up dying without reaching the boss of the portal and you need to know how each boss works, how to kill it what is each boss weakness.