Your first character has +10 Attack
Haunted Helm is a Level 3 treasure in Storybook Brawl.
This is a very powerful treasure that retains its value for most of the game. It’s especially useful if you have a character in you first (front right) position with a powerful Slay ability (eg Jormungand) or when you’re playing a Slay heavy build (eg using Sad Dracula, possibly with Shadow Assassin.
The equivalent of this treasure for Health is Haunted Helm. Personally, I’d usually choose Haunted Helm over Sting.