The classic flamethrower. Primary fire shoots the selected mode, either classic flames, or a stream of ice. Alternate fire switches between modes. They have a few seconds to pick up health and stop the effects, but after that, they explode in a Redeemer-like blast, killing them and almost anyone around them. The FBR has a low rate of fire, but even that doesn't make up for its power.
Alternate fire shoots one rocket.
If you move forward while shooting, the rockets will probably hit you, so try moving backwards. Just what it sounds like. Primary fire shoots ice crystals that bounce around until they hit something or disappear on their own. If you do enough damage to someone with this, they'll freeze, leaving nothing but a shatterable ice sculpture. Alternate fire shoots blobs that stick the the ground, and have the possibility to freeze anyone who touches them.