A brawler is a monster from the Pest controlminigame. They are often considered irritating monsters because of their ability to stop players and monsters from walking through them, sometimes preventing players from reaching spinners or running to the next portal.
During the game they do not attack the Void Knight, so it is not vital to kill them. They have a lot of life points and fairly low Defence, which makes them very good for quickly raising the player's total damage.
Ava's devices do not collect arrows when shooting at these, as is the case with most large monsters.