How many Characters can one player have?

im trying to change os from windows to linux mint for personal reasons but i still wanna play the game.

everytime i try to start it its saying "this program cannot run without directx runtime" i did reinstall both dx9 and 10 and its still giving me this error

I'm struggling in the nightmare phase simply too much happening and i feel weak. /spoiler]

I'm stuck on the Undying King boss in the campaign. I watch some videos on how to beat. In all those videos they have 5 to 9 dragon hearts. I have 4. I watch videos on how to get more dragon hearts. They suggest to farm the crafting mats in adventure mode. Adventure mode on normal is 10 x harder than the campaign and I die on first area. WTF?...