Trials of Justice. v20 of the game increased the difficulty of the final level of bosses. On the whole I don’t think it was that much harder but it is noticeable if you look up the bosses HP. I don’t think this quest is beatable by a team of 4-star classic heroes. It might be theoretically possible with enough Cyprians and Wu Kong to color stack purple against yellow bosses.
I ended up using Leonidas, 2 x Joon, Aegir & Wilbur.
This video jumps straight to the boss wave.