Like all other games, Games has a Final Boss.
D4’s Final Boss is Uber Lilith. Of course, at the highest difficulty, this Final Boss is hard to beat.
That’s why there’s game difficulties. There is WT1 and WT2. Most players has beaten the Campaign on WT2. That’s the game. It’s GG for them.
But if you are better than WT2, there is WT3 and WT4 for you.
WT3 has Sacred Armors. There are Nightmare Dungeons on it from NM1 to NM20. Its Final Boss is Capstone Elias. Beat him, and you would access WT4 Torment, the hardest difficulty of the game.
WT4 has Ancestral Armors. There are Nightmare Dungeons from NM21 to NM100. Its Final Boss is Uber Lilith (Echo of Lilith). Beat it and you could say you win the game.
My only issue is when ramping up from WT3 to WT4, it’s a bit hard. You would feel super powerful on WT3 and when you reach WT4, you might have a difficulty to kill its trash garbage mob/s. But once you overcome it, it would be okay. But NM100 and Uber Lilith is painful to a regular player… impossible for inexperienced player.
When you get one-shot killed on high NM dungeons on Torment WT4, it’s normal. It’s not bug’d. It’s a feature.
Good Luck.