What happen to your Char. if you beat or fail it?

You are rerolled to lvl 1 regardless of the outcome.

Okey, if you beat Mq you will unlock secret chars, if you are feeder class (fighter,barbarian,magician or rouge) you will unlock Samurai, otherwise you will unlock next secret chars.

You will be reroll to level 1 with all your gears and items on market place without class, then you can use "change class" and chose new one.

Otherwise if you fail Mq you will be reroll to level 1 with gears and items on market place, but without a new class ^^