I used to love those old "choose your own adventure" books, and I love these little adventures. Certain things do need some clarification, and the books could use some erratas in places.
I don't think it's ever clarified what happens if your opponent and you roll the exact same result on a battle. I've made a personal ruling that you hit each other at the same time, and you defeat the enemy but lose one life.
Also, in the Arena of Doom adventure, at one point you can get a potion which prevents the enemy from making you lose your die roll in combat, However, I've checked and there doesn't seem to be any enemies with that ability in the book, so I'm ruling that the potion prevents the enemy from imposing penalties on your die roll for one combat instead.
That being said, I love these books and I'm very much looking forward to the next in the series.