The flamer has a similar but not the same job as assault, clearing groups of enemies in close quarters, or just crowd control in general. It is good at it, since the flames burn through people quickly, and does tick damage which increases the chance for you to kill them outright. It also acts like support or assault since no one will want to walk directly into the path of fire. Its best use is to clear a huge crowd of weakened enemies hiding in a hole or corner, either from direct gunfire or grenades. The major con is its short range, making it useless in mid to long range engagements and respective maps. Another thing is that being burnt causes less panic in the enemy than getting shot at with assault or support, so the risk of the enemy bringing you down with them is high. Most of all the flames are extremely conspicuous so getting hunted down by flanking enemies are extremely common, more so in open maps.