If I could buy an endless non-dead try out with pinnacle boss or any monsters

Guys, after 1000 hours with POE2, I'm thinking what is the most wanted game feature for me, and it is:

A method by paying currency to fight any choosen boss or monsters without killing each other, so I could learn the movement to fight them in the real combat. Because even if I could buy tickets to those pinnacle boss, I might still be dead by one shot, or other mechanics.

If thers is a feature like this, I could really pay and spend time to learn and then fight as what the Vision want me to, I just don't want to die by not-knowing one shot.