Uncorrodable Cyberwalls

Destroy the runner's fracter with Power Shutdown or Wisp it. If you can't, tax him heavily with strong barriers supported by Lag Time and Superior Cyberwalls. If the runner still manages to steal agendas, Punitive Counterstrike him. Grim deserves a special note here, as the runner might start to think you have nothing but barriers and so won't bother to install a killer.

I've chosen GRNDL as the ID because the bad pub won't mean anything if the runner's breakers keep disappearing.