3 times this has happend to me. I'm just walking down the sidewalk in a dungeon and all of a sudden I'm pulled into a battle. The first time i was playing with my friend, so we dealt with is quickly. These two times now drove me insane. I've been trying to finish this dungeon and I defeated the first boss easily. I was so happy. But then, I was walking down the sidewalk and I'm pulled into battle. I dealt with it and i was steaming mad. I walked back to the sidewalk and got up to get a glass of water. When I came back, I was in another battle! This is really making me angry!
Is that the dungeon where the death school is? If it is, I have noticed that you can be pulled from the side walk which makes it a challenging dungeon which I think is the point of it. Sometimes you just have to expect it from these type of dungeons.