The Precursor Sentry is a boss from Jak and Daxter: The Precursor Legacy VII. It is fought at The Waterworks. This metal-headed guard robot attacks anyone who activates it. Unfortunately, it is the only thing capable of destroying the Lurker dam preventing the river from flowing south. To start the battle, get a Blue Eco charge and walk up to it. This will breathe life into the machine, but you'll now have to undo this action.