The blue line is the fibo 50% middle line of a day candle. When bull and bear fight, the forming of bear and bull, need to break the Fibo 50% line first, once it break, the winning party will go to the 1.618 target line. To use this indicator, you can observe how it react at the middle line, if it win, you may set your take profit point as at te dotted line (1.618) at the time of rebound.