Finish the meridian missions. Tarkus will get it. Also, I've run into two other sets of terminator armor in random missions as rewards. It's pretty amazing. Check the stats! Link On a side note, with proper traits, all but your scout squad can equip terminator armor. I'm not sure if you could actually equip all four squads with it at the same time, as it's pretty rare. Still, each squad becomes insta-win with it on.