To get the exterminator cards you must:
Shellshock - Obtain all weapons and omega mods.
Reactor - Advance all weapons to mega version
Eviscerator - Obtain 100 Nanotech
Ace Hardlight - Obtain 400.000 dread points
Vox Card - Obtain every skill point in all plannets
Slugha Card (Vox's Pet) Complete the game (including dread
challanges) on Exterminator difficulty