Charging Needler glitch
From Halopedia, the Halo wiki
The Charging Needler Glitch is a glitch that only works on the Halo 2 level, Sacred Icon. It can only be done when you have Jackals as your allies.
Walkthrough
To experience this glitch, you must play the Sacred Icon until you find the Jackal and Grunts, which are located at the beginning of the level.
Destroy all the Sentinels and the Sentinel Launchers to stop any Sentinels from coming out. If the Jackal is charging his Plasma Pistol after the battle, switch it with a Needler. If done right, the Needler will fire, but no Needles will come out. Try it with other weaponssuch as the Plasma Rifle, or any other weapons you can find. If you give him the Plasma Rifle, he will fire and overheat it.
