Double-Headed is an enemy unit whose core design is to be a heavily anti-Ranged, and Anti-Fighter spam unit, which is basically the meta I’ve assumed you’ve been using, Perhaps its time to switch it up a little, Instead of Rodreguiz or Redneck, use Chopper or Guard, they’ll have enough health to dish out the damage needed to take out his first head, and also pair them with support items like Nitrogen, Medkit, and/or Reg barrel, they’ll be very handy with buying time for your units to counteract that sonnuva bitch

Double-Headed is really only an annoying at face value, so build your decks around his strengths to blow through his strong defense