Ptolemy Keraunos wasn't that good a general from what I understand, the Keraunos part of his name means "thunder" and was given to him becuase of his rather headstong nature. Amusingly the Celtic leader that defeated him was named Bolgios, which has a similar meaning.

I also recall reading about the Celts rolling under the spears of the phalanx so they could get in close, where they would have the upper hand, I don't know if it was used in this specific case though.