deirdre 's tangle of living locks danced with purple saint elmo 's fire , lashing out in a deadly webwork , but ivy constantly cast out a spinning cat 's cradle of light , tiny , tiny threads of power that did not so much stop any of deirdre 's attacks as they fouled any one of her locks with others near it , tangling them together into useless clumps-sort of an enforced bad-hair day .