The Z-2500 Automated Protection Drone, also known as Autosentry, is an Armor Ability featured in Halo 4. It allows the user to deploy a combat-capable Forerunner drone unit as support during enemy engagements.
- Main article: Halo 4
- Autosentry can kill a fully-shielded SPARTAN-IV in 6 shots.
- Autosentry supplements firepower, since the player and the turret can attack simultaneously.
- Autosentry can be used as an alarm. When an Autosentry detects an enemy player, it lights up red and begins to fire. The sight and sound can alert the user of nearby enemy players.
- Autosentry can be used as a distraction. Opponents targeting the Autosentry may not be aware of what the player is doing.
- Autosentry can be used to deny access to an area or defend key locations such as Flags or Hills. Opponents may stop to take out a player's Autosentry before advancing.
- Autosentry's projectile speed is slow, which causes its accuracy to decrease as an opponent's lateral speed increases.
- Autosentry does not have much health.
- The player is vulnerable while his Autosentry deploys.
- The Autosentry is fooled by holograms.
- Other human-originating APD units similar to the Z-2500 have been used by the UNSC for years, but none with this level of mobility, functionality, and sustained power.
- Autosentry is similar to Halo 3's Automated Turret.
- In the Halo 4 mission Midnight, there is an alternative type of APD available in the armory before entering the Ur-Didact's atrium after the conveyor. The player will be prompted to swap for it even if he already has one equipped.
- In Halo 4, the Autosentry is used by Promethean Knight Lancers and Battlewagons.