How does Galvanic Field of Intensity work?

Been trying this skill but it's kind of hard to tell. So I click the "buff", then when I hit an enemy, it casts a "ring" around it. Then it does damage to the target and the monsters around it ? Or just the surrounding enemies?

Do I need to keep shocking to make it cast Beam?

I would say just once, then it lasts for a duration. I've only used the standard version though so may not be accurate.