Seething Sigh has been defeated at last! :D Do bossess get worse?

After numerous team compositions I've managed to kill the boss of act 2: resentment! In the end, the man, the armour, the Crusader was the missing part in order to ensure the kill on the boss through support.

Wow this boss was a wall, and pure Hellion dmg was needed to break it. But are bossess in next acts worse?