As Terran
Make:
Viking
Raven
MarineAir control removes the zones before ground units have to move.
Open in the counter tool with Liberator tagged ->As Protoss
Make:
Tempest
Stalker
PhoenixBlink under isolated Liberators, or outrange them with Tempests.
Open in the counter tool with Liberator tagged ->As Zerg
Make:
Viper
Corruptor
HydraliskAbduct is the cleanest answer to a defended Liberator line.
Open in the counter tool with Liberator tagged ->
Marauder
Reaper
Hellion
Hellbat
Widow Mine
Cyclone
Siege Tank
Thor