A dragonfly doji has open, close, and high all near the same level with a long lower shadow. The long wick shows bears pushed price sharply lower but bulls fully recovered it by the close.
Strong bullish reversal at lows. Bears drove price way down but bulls absorbed all the selling and pulled price back to the open. A longer lower shadow means more aggressive bull counterattack.
Signal is strongest at downtrend extremes or near key support (win rate 64%). Enter long when the next candle confirms with a bullish close. Stop-loss below the wick's low.
Most meaningful at downtrend bottoms; less significant at highs. Longer shadow near important support = higher reliability.