Autogun

The Auto Gun is a Combine weapon seen only in the chapter "Under the Radar". It was used to stem the flow of new Zombies pouring out of City 17, but it also (as a side benefit to the Combine) blocked supply runs to White Forest. It had five blue searching beams that behaved like Snipers (with their obsession with killing birds), but fired much more powerful pulse lasers which cause instant death. It can only be defeated by sneaking around behind it and dropping a Grenade into its systems.