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.

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.

List of appearances

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