Vitality got reworked.
Doombringer has not.
Doombringer, on Insane and Madness, have a couple of very brutal tools that are both extremely difficult to play around as well as extremely unfun to face.
Let's take a random boss that I've encountered as an example.

Hello, Ivanor!
With just shy of 20,000 HP and about 50% resist all, this beast is a force to be reckoned with! Fitting for a boss-level unique! While I believe to have an epic fight ahead of me, there are certain abilities that are about to make this less epic.

Wraithform, with just over 50% uptime, proves to be a very potent tool in sheer stats alone. That's a lot of armor and defense on a buff! That, and he can phase through walls. This means, no matter how much you try to hide, he will be able to root you out and likely double-team you with anything, no matter how hard you sequester yourself off.

Every 6 turns, 400% of an impressively high Weapon Power will come striking down upon me, both healing him and more importantly restoring his VIM to a very high amount. With such powerful regeneration available to him, he's prepared for a lot of sustained damage. Perhaps we can burst him...?

Surge of Power guarantees, should his healing mod not be 0% and/or Nexus of Healing is not up, that this fight will last forever. With 19,000 HP, he stands to heal far, far more then even a very powerful character's DPS allows. Mind you, he's only level 50!
In Madness, enemies easily breach 100 later on. That Surge of Power will only scale harder. Wraithform allows him to chase, his impressively high physical damage allows him to hit hard and fast, and Surge of Power allows him to never run out of health.
In essence, Doombringer is a cool class with scaling issues for enemies as their talent levels go higher and higher.
Please, Darkgod, tone these beasts down a notch.