Sentinel launcher

Sentinel launchers are small armor-covered devices built into the walls of Forerunner facilities. They can be found in numerous locations, such as the sentinel wall, the control room, Installation 00's cartographer, and the Absolute Record.

Overview
When hostile entities, such as the Flood, are detected in the immediate area, the sentinel launchers open their covers and dispense Aggressor Sentinels. When releasing an Aggressor, the launcher emits a noise that increases in pitch until the Aggressor appears.

A sentinel launcher is at its most vulnerable when its armored cover opens to release an Aggressor. It is the most susceptible to overcharged plasma pistol shots, plasma explosions, and even physical attacks. Upon destruction, a sentinel launcher emits an electromagnetic pulse to its surroundings.

A sentinel launcher, however, is linked to Sentinel Defense Network on Installation 00. When Voridus disabled the Defense Network, the Sentinels cannot launch from it, resulting in the Flood are able to clog many of Launchers due to the network is inoperable. When the Defense Network is reactivated, the Sentinels are once again can be launched to resume their duty.

Gameplay
In Halo 2, sentinel launchers can only be found in the campaign level Sacred Icon, and consistently release Aggressors to combat Flood combat forms and Thel 'Vadam.

In Halo 3, sentinel launchers can be found in the campaign levels The Ark and Halo. In addition to being allied with John-117, they are also more durable and release Aggressors at a quicker rate than those in Halo 2. In addition, the hatch closes immediately after the Aggressor is released to prevent weapon fire from getting into the launcher, although this can be bypassed by throwing a grenade before it closes.

In Halo Wars 2: Awakening The Nightmare, Protector Sentinels and Aggressor Sentinels mainly appear from Sentinel Launchers. They can only be disabled temporarily by Voridus' EMP fields and when operating, they come in an endless wave.

Trivia

 * With the Rocket Launcher, you can lock onto Sentinel launchers as if they were vehicles.
 * In Sacred Icon, there are many destroyed Sentinel launchers found throughout the level. Despite appearing destroyed, these launchers can be destroyed again(with the armored cover falling out). This is easily seen in the gondola room where, after pressing the holo-panel, all the Sentinel launchers are destroyed, including the ones that are already destroyed.

List of appearances

 * Halo 2
 * Halo 3
 * Halo 2: Anniversary
 * Halo: Escalation