When you reach level 3, get two spells that let you pick a new hero.
Mask is one of the advanced Heroes in Storybook Brawl.
Mask is more of a ‘meta-hero’ than a unique Hero, since its only ability is being able to change into another Hero twice per game. It’s a powerful ability, but deciding when to do this and which Hero to switch to is complicated. Mask is probably one of the most difficult Heroes to play well.
List Of Heroes