Needle cannon

Introduction
The Heavy Needler is only seen in Halo 2. It is first seen on the level Sacred Icon when Tartarus explains to you how to destroy a Sentinel Enforcer. If you stay alive long enough, the Enforcer will start to shoot at you with its Heavy Needlers, which fire crimson needles that are larger and more powerful than the weaker purple variety which the Covenant use. These needles don't home in on a target or explode on contact, but still pack quite a punch and can take down the Arbiter (you) after a couple of direct hits. This weapon is particularly useful against the hordes of Flood that the Sentinels face and was most likely developed specifically for combat use against an infected lifeform. The Enforcer will attack you with it on the levels Sacred Icon and Quarantine Zone.

Use
The Enforcer will only engage targets with the Heavy Needler that are few and far between, such as the Arbiter, and very small groups of Flood. The Enforcer is not known to otherwise engage targeted hostiles with this weapon.