The Prototype Doll Staff is a Hardmode sentry summon weapon that summons a Goliath Doll that lasts for two minutes and does not count towards the minion limit. When enemies are nearby, it will swing a Goliath Sword that fires a magic projectile, at a rate of once every two seconds. Both the Sword that the doll swings and the projectile it fires out can do damage. The Goliath Doll can be spawned anywhere on screen as long are there are blocks or platforms for it to stand on.
Once the Goliath Doll has been around for 110 seconds, it will start sparking and, once its duration is up, it will explode. When the Goliath Doll explodes, it has a chance to drop the Goliath Sword.