Police Drones
Brought into Paragon City by the PPD after the Rikti War, the Paragon City Police Drones are small hoodlight-looking robots that patrol Paragon City and keep citizens (and heroes in need) safe. They are typically stationed at zone entrances (including the Paragon City Monorail stations) as well as some areas of high importance to the city (such as Atlas Plaza).
The Police Drones are also stationed heavily around the hero bases in Player Vs. Player zones, along with plentiful Longbow, so Villain Players are less able to assassinate heroes in those areas.
The in-game mechanism for the method that drones instantly defeat foes is based on Portal Corp technology that teleport foes directly in to prison - usually The Zig in Brickstown.
The drones con as Sentry, are invincible, have absolute accuracy to all villains, and always defeat villains in one hit, no exceptions, even in PvP zones. However, they can only attack one enemy at a time and have a small delay between attacks, so a large group of enemies has a small window of time during which they can still attack.
The drones do differ from the Paragon Police Department drones spawned in Mayhem Missions, which look identical physically, but have a damaging attack rather than instant defeat of a Villain.
Drones also provide a perception buff to nearby heroes.