A simple extension of the Wavedash, it can be performed out-of-shield. This lets you punish large but shield-negative moves like Marth's forward-smash or create distance if you feel a punish is too risky.
When dealing with opposing Fox or Falco, shield pressure situations are likely to turn into 'shine war' due to shine's immense safety and speed, making this option somewhat less reliable.
It is particularly useful against Marth and Shiek, whose moves can be hard to punish with grab or an aerial.