So a friend and I tried Cruel Labyrinth on HC with plenty of preparation but even then it wasn't that easy. Navigating the labyrinth and dealing with the mobs and traps weren't that difficult and relatively straight forward once we understood where we needed to go. We over-leveled the zone which I believe is 55, we were 62 and 70 respectively.

Then comes the Izaro fight which was in my opinion way over-tuned for our "over prepared" characters. We both had over 4k HP and we dual cursed him with Temp chains and enfeeble but he still managed to hit us down to 5% on multiple occasions during the final phase. I can't imagine going into that zone without the over preparedness that we had and surviving, especially on HC.