In this chapter, we learn that the metamorphoses are using a "combined attack" strategy, which means that they're using all four of their attacks at once. This means that the two of them can't attack at once, and they'll have to work together to get rid of the other three. This is a big problem, because it means that if they only attack one of them, they won't have enough time to do anything against the other two. The only solution, says Mr. Lorry, is to use the "third move demon spell" on the two who surrender, and if they don't, he'll kill them.