Practise mode for Bosses

Hi!

Would be good to have a Practise/Test mode for Bosses.

However we are trying to learn what to do there it is much different watching some video, reading the mechanics than actually doing it with our hero, which could be much less capable to handle it. Less damage, defense or simple different playstyle.

On the other hand we are never sure if ready for a fight or need to improve.

Thank you!