The Beast Rider himself is actually one of the most docile enemies you could encounter throughout the game. He tends to come equipped with either a Hammerburst or Boltok Pistol which he fires at a relatively slow rate compared to other Drones. The real danger of these enemies is the variety of beasts that they ride.
While Beast Riders can ride just about any mountable creature (including the Brumak), you'll most likely encounter them astride Bloodmounts or Reavers. Each of these enemies is devestating in their own right and you should check each page for help with dealing with the mount itself since each has its own strategies. The Beast Rider himself, however, will simply shoot and "drive" the beast. If the mount is killed before the rider, it is possible for the rider to survive and continue fighting. When this happens, he will act like a basic Drone or Grenadier. Keep in mind that killing the rider first instead of the mount can result in the mount becoming more dangerous.
