Dreadnaught
Armed with a flamethrower and enough fuel to torch a small city, the dreadnaught can do more damage at close range than any other enemy. Keep your distance and you should be safe.
If you do catch fire, dive into the nearest water, pick up a health pack, or simply wait -- the fire will eventually burn out. Wearing a biosuit helps, too.
Centurion
The centurion’s flying platform allows him to overtake targets quickly, but his high-powered nailgun is dangerous even at a distance.
Some centurions have learned to exploit the experimental technology of the flying platform to "phase" through solid matter. It is not currently known how this works.
Automaton
These security robots were commonly nicknamed "Floyd" becayse of the FLD model designation. Their corroded metal brains are not sophisticated enough to understand fear, hesitation, or doubt.
Be careful -- each automaton is powered by a primitive atomic core that will explode if breached! On the other hand, that could be useful...