“Forerunner” is the first mission in Halo 4 where you will encounter Prometheans, a faction of enemy new to the Halo franchise. In addition to new enemies, there are also new Promethean weapons that you will begin encountering in this mission. You will mostly use the light rifle, which is a 3-shot-burst headshot weapon similar to the UNSC battle rifle. You will need to use the light rifle as your headshot weapon throughout this mission. The Prometheans do not use covenant weapons, so you will rarely have access to a plasma pistol when fighting the them. Therefore, when you are fighting Promethean knights (the Promethean equivalent of elites), you will need to use different tactics to remove their shields. For the majority of this mission, you will use the Promethean suppressor, a fast firing assault rifle that deals high damage up close. Use a combination of your auto sentry (an armor ability), grenades, and suppressor fire to kill the Promethean knights. It is vital that you fight them alone, so be sure to kill any crawlers or watchers (the Promethean light infantry) in an area before you engage the knights.
You begin this mission inside of a forerunner teleporter hub with an assault rifle, a magnum, and a hard light shield. The hardlight shield is a practically useless armor ability, so swap it for one of the auto sentries located on the walls to either side of you. The auto sentry armor ability allows you to create a stationary, hovering turret that fires upon the enemies. Enemies will tend to shoot at the auto 7.62×39 ammo sentry instead of you, so it provides you with a great distraction. It also deals a fair amount of damage, so it helps you kill knights when fighting them with your suppressor. Once you launch the auto sentry, press the bumper again to recall it.
Walk into the main room of teleporter hub and insert Cortana into the mainframe. She will then create a teleporter to the first relay tower that you will need to disable in order to contact the UNSC Infinity. Jump through the vortex, and you will teleport into a cave a little ways away from the first relay tower. As you follow the path forward, you will see the first Promethean enemies; crawlers. Crawlers are somewhat similar to grunts; they can be killed with a single headshot and they wield the weakest weapons. Notice that the crawlers have much smaller heads than grunts, so you will need to aim carefully. Use your magnum to kill these crawlers with headshots, using the corner of the path as cover. If the crawlers begin to overwhelm you, launch your auto sentry and it will drive them back.
Follow the path until you turn into a large open area. Here, you will find 6 crawlers, a watcher, and a knight. Use the corner you just came around for cover and kill all of the crawlers first with your magnum. As long as you stay back, the knight will not approach you. Now, turn your attention to the watcher. Watchers are support infantry capable of shielding enemies, reviving knights, catching grenades, and spawning crawlers. Watchers do not have heads, so you usually need to kill them with multiple body shots from your headshot weapon. In this case though, your magnum is not strong enough to kill the watcher, so get up close and kill it with your assault rifle instead. If necessary, launch your auto sentry to draw the knight’s fire while you engage the watcher.
Now that only the knight remains, you can focus your attention on him. Knights are similar to the covenant elites, but they have stronger shields and smaller heads. This knight is equipped with a light rifle, which gives him high accuracy but low damage. Therefore, get as close as possible so that he cannot utilize his accuracy advantage. Launch your auto sentry so that it has a clear shot at him, then get up close and use your assault rifle to kill him. After his shields break, continue to shoot him with your assault rifle until he dies. Prometheans have much more shields than health, so once you see their shields break, you know they are almost dead. Swap your magnum for his light rifle, grab his pulse grenades, and swap your assault rifle for one of the crawler’s suppressors. Move into the forerunner room up ahead.
As you walk through the hallway, you should see two crates along the left wall with suppressors that you can use to restock ammo. As you exit through the door, a knight with a suppressor will attack you. The suppressor deals more damage per second than the light rifle, so you will need to be more careful when fighting this knight. Stay inside of the forerunner room and launch your auto sentry once the knight comes within range. Use the doorway as cover and step out to fire at him. Use your light rifle when he is far away and use your suppressor once he gets up close. If you see the knight stop to throw a pulse grenade at you, immediately throw a pulse grenade at his feet. Because knights cannot move when throwing grenades, you can easily get a direct hit from the explosion. Once his shields break, either charge up and finish him with your suppressor or stay back and finish him off with a light rifle headshot if your shields are low. Whatever you do, do not allow the knight to escape when his shields are low because his shields will regenerate very quickly.
Killing knights with headshots is much more difficult than killing other enemies with headshots. Not only do knights have the smallest heads of all of the infantry in Halo 4, they also have face gear protecting their head. While they sometimes detract this face gear naturally, you usually need to shoot them once in the face gear after you remove their shields to force them to retract it. Only then can you finish them with a headshot. 3-shot-burst guns like the light rifle or battle rifle can kill an unshielded knight with a single trigger pull because the first bullet removes their face gear and the second bullet kills them.
Move forward along the path to the left and you will come to more crawlers and a knight with a light rifle. Launch your auto sentry to draw the knight’s fire, kill the crawlers with light rifle headshots from the cover of the rocks, and then kill the knight with your suppressor. Notice that every knight drops two pulse grenades when they die, so feel free to use plenty of pulse grenades when fighting Prometheans. When you find yourself in a tough situation, you can throw a pulse grenade at a knight or a group of crawlers to cause them to dive away, giving you plenty of time to retreat to cover.
Continue down the path and you will come to a platform with many crawlers on the walls. These crawlers will begin jumping towards you once they see you. Kill them all from a distance with your light rifle. Run onto the platform and up the ramp to the right where you will find a Promethean crate with light rifle ammo. Restock on ammo and move to the forward edge of the platform where there is an opening in the wall. This opening provides you with a good sniping position over the enemies below, where you should see more crawlers, a watcher, and a Promethean battlewagon. Battlewagons are a higher ranking version of knights, and they are equipped with stronger shields and a scattershot. The scattershot is the Promethean equivalent of the UNSC shotgun, and it can kill you with a single shot up close. Therefore, you should engage battlewagons from a distance whenever possible.
Use your elevated perch as cover to kill all of the crawlers below with light rifle headshots. Step behind the wall to your left for cover if necessary. Kill the watcher with 3 – 5 body shots from your light rifle. Notice that the light rifle deals more damage when zoomed in, so be sure to use the scope when fighting watchers. As soon as a watcher starts glowing red, it only takes one more shot to kill it. Now you can focus your attention on the Promethean battlewagon. Because he is equipped with a scatter shot, you will need to engage him from a distance. If you stay where you are, he will come up behind you and kill you. Therefore, you should jump down into the area with the battlewagon, sprint through the cave along the right wall, and sprint up the dirt ramp to the top of the cliff ahead. The battlewagon will usually not follow you up here, so you can pick him off from a distance. Launch your auto sentry and then bombard him with either suppressor or light rifle fire until you kill him. If the battlewagon stops to throw a pulse grenade, throw a pulse grenade at his feet to kill him even faster.