How hard is master mode?

I’m currently on a play-through of master mode on a normal character (whatever one drops coins on death). I’ve beaten the game once on the easiest difficulty with my cousin and honestly it was a breeze. I’m not exactly new to terraria I played it since it’s release just haven’t actually tried to get anywhere with it. For some reference, I only recently figured out about classes and play summoner, I plan i doing the master mode run solo and I’m yet to decide a class, any information on how hard it is and if I should know anything before going into it would be appreciated, thanks.