I like the card. It has it's uses. At the right time, it can do just enough damage to score some KOs. But in my experience, it just takes up space that other cards can fill (evilolite). For extra damage, I'd take plus power. Sure, it's only 10, but it's the element of surprise. Playing it at just the right time can win you games. On the other hand, rocky helmet can be countered (catcher, tool scrapper, and just not attacking). Smart players will know how to get around it.
I'd give it a 7: It's not bad on it's own, it's just doesn't have a place.
Artwork: 5