remove restore life from boss the Ultimate zone
The Ultimate Zone (Eternal Libray, Dusk Pirates den, Eeri's Library) are a bit easy to do when being has the recommended CR plus the problem and that has a time limit to can kills the boss before he gets the HP back.
I have a suggestion of remove the HP Recovery effect from the boss when our character dies and before time runs out and the boss recovers HP.
since even if you have 1,350,000 or 1,900,000 CR to make Eeri or Eternal and almost impossible to kill the boss before time runs out and does not help much You take 60% of HP of boss and you die and restore the HP of the whole boss.
I think that this system of these 3 Ultime zone is very bad and forces a CR much higher than the recommended.
forces the win without dying even 1 times and still before the time ends and the boss recover HP
if you can remove that part of the HP restoration would be a blessing