Brawler.

Zsymon

Brawler creates a shield depending on how many enemies you hit with it, but does the shield keep increasing as you recast Brawler or does it just refresh the shield with a new cast?

Sproeikoei

Answer:

Any consecutive cast of Brawler does not add a new shield until the previous shield has dissipated.
So my advice is to time and aim it well to get the most shield-points every time you use it.