Miniature Spartan glitch

The Miniature Spartan Glitch is a glitch that can be performed in campaigns of Halo: Reach and Halo 4. It causes the player model (SPARTAN-B312 or John-117) to shrink to a small size.

Method
This glitch can be performed on the Halo: Reach level ONI: Sword Base and Halo 4 level Composer. It takes advantage of a de-spawn trick used in the level design of both games. To create the illusion of spacecraft flying rapidly off into the distance, without running into draw distance issues, the developers shrank the spacecraft as they fly away. This makes it seem as if the spacecraft is farther off in the distance than it actually is, allowing it to de-spawn inconspicuously. This mechanism can be used to shrink the player model: if a player is riding as a passenger in or is boarding as spacecraft while it is shrinking, they will shrink along with it. The player will then be left as a miniature Spartan, in some cases able to pilot a miniature spacecraft, although all player weapons will remain their normal size. This glitch uses the same operation which allows a full-sized Spartan to pilot a miniature Type-31 Seraph in the pilotable Seraph glitch. Its effects are also similar to those of Halo 4 ' s Miniature Covenant glitch, the mechanics of which are unknown.

Tutorial - Composer
This glitch is performed in the composer room when you fight against the Covenant. On a platform in the middle of the room to the left is a Banshee. Quickly run to this, and kill the Elite who runs to man it. Fly it over to the building near the hangar opening, lift 03, that you normally would exit when you are done. Park it near the door, and clear out the enemies.

When the first wave of banshees comes, make your way back to your parked banshee. Remain on foot and destroy all enemy banshees. Then, enter your banshee and wait by the door. Another wave of enemies banshees will follow; do not destroy any of these. In a short while, dialogue (between Master Chief and Cortana) will play, and if you are waiting near the door, a loading point will be triggered. Once this occurs, fly out to intercept the banshees as they are leaving the map. Just as they are about to leave, dismount your banshee and board one of the enemy banshees.

As you board the enemy banshee, it will begin to shrink. If you timed it properly, you will shrink along with it. You will remain inside the map, and will be able to pilot the shrunken banshee.

When you dismount, you will find that your player model has also shrank. Your point of view will be lower to the ground, but your weapons will remain their normal size. The size change won't prevent you from performing normal actions (e.g. operating turrets).