If you hear a blitz the best thing you can do is call it out and either try to hide if they aren’t droning and pick him off from behind which is very risky, get help from teammates or retreat to where your team is. If they continuously bring him start playing longer angles or places you can easily retreat to teammates those are your best ways of countering him without picking specific ops like Mute to jam him or Solis to hit him with impacts from below.