How much percentage of damage does the Railgunner's Supercharge deal?

What is the only attack in the game that has a proc coefficient of 0.1?

Köppen As F̷̬͈͚̃̄̚ὐ̶̻̃̉͠¢̵͉̩͇͍̒̾̕κ̸̢̻͆̔

..and so she vanished, never to collect again.

..and so she vanished, her momentum halted forever.

..and so she vanished, her place forever vacant.

..and so he left, with dreams of good food and a peaceful night. 

..and so he left, with new orders and new questions.

..and so he left, grateful for his luck. 

..and so he left, with newfound inspirations.