Lately I have been under the impression that a lot of people are having a hard time killing Prometheans quickly. I don’t think many people realize how powerful suppressors or boltshots can be against them, so I’ll just post some methods on how to kill them quickly.
In general, except for enemy vehicles and knights, running Prometheans over with vehicles is one of the quickest ways to kill them. Running them over is an instant kill. This is most effective in maps that is wide open and offers no cover. This is good, because otherwise your only other option is to spam rifle bullets until they die, which is time consuming. Keep in mind that spamming shots from far away is a viable strategy depending on the situation.
Prometheans do not use shields like the covenant do, but rather they use armor. Promethean armor cannot recover by itself, it can only recover through watchers. Otherwise if their armor has been stripped it stays stripped. Promethean armor take extra damage from hardlight shots, mainly from suppressors and boltshots.
So in the case where you are not running them over, these two guns will be your best friend against prometheans if we exclude power weapons. Power weapons work as well but the ammo is often scarce and not easy to renew. Both the suppressor and boltshot work similarly so it is really not necessary to carry both.
Precision weapons are weapons that can kill on one shot to the head (battle rifle, magnum, dmr, etc.) They are also going to be very useful against not only the prometheans but against most enemies as well. Boltshots and Suppressors are not precision weapons. They do not do extra damage if they strike the face nor can they kill with 1 shot to the head. So it is important that you bring a precision weapon in addition to a suppressor or a boltshot to kill your enemies quickly.
–Crawlers–
Crawlers die easily to headshots from precision weapons. This is often the quickest way to eliminate their numbers. Crawler’s head hitboxes are not located on the border of their body when they face you, so it can be tricky to headshot them. Consistently headshotting takes a bit of practice, but when improved the results will speak for themselves.
–Soldiers–
Use suppressors and boltshots to strip their armor (you’ll know when it’s gone when their body and face turn bright). When stripped, hit soldiers in the face with a precision weapon to instantly kill them. Soldiers also take bonus damage if they are hit in the middle of their chest. This is easily accomplished with the two aforementioned weapons which serves to boost their effectiveness.
–Knights–
By far the best strategy against them is heavy vehicles such as wraiths and scorpions. Hitting them with cannon shells will kill them quickly. However it is often the case that heavy vehicles are not available. In which case it is best to engage them on foot.
Hitting their side cores is most effective. It is easiest to hit the cores if the knight is facing you. The cores can be easily eliminated with suppressors and boltshots. Each time a core is destroyed the Knight will open its mouth for a small instant. If you can hit the mouth with a precision weapon, they can be instantly killed. If both cores are destroyed the knight defenses goes down and it takes more damage from any attack inflicted. Generally it is best to hit the back core from behind with suppressors or boltshots or to remove the face plate in front with precision weapons if both cores are destroyed. When the face plate is removed the head is exposed, in which case it will only take one more shot to eliminate them.
Also note that knights can be assassinated if both cores are destroyed. This includes knight bosses.
–Watcher–
Suppressor and boltshot to kill them quickly, otherwise just keeping shooting them until they die. Do not use grenades if watchers are nearby, they can catch them and throw them back
–Warden–
Probably what I consider to be the bullet sponge of the prometheans.
In the legendary campaign he actually has less health than he does in warzone and firefight. What worked in the campaign was to get a strong power weapon (an incendiary cannon or a railgun) and keep hitting him until he got stunned. Then while he was stunned, take a shotgun or scattershot and keep hitting him in the back until he recovers or he dies. If he recovers, stun him again with the other power weapons and repeat. What also worked was tossing plasma caster grenades behind him so that the blast radius hits him in the back.
Unfortunately in warzone he does not get stunned as easily and attempting to shotgun him in the back often result in death. He also has a massive increase in defense. But what is available is heavy vehicles such as wraiths and scorpions. Having a team just spam tank shots at the warden is what I found to be the best method to defeating him. Wraiths work particularly well when he spawns at the bases of firefight because the shots can ark, therefore allowing you to hit him in areas you otherwise couldn’t but scorpions can work as well if you can get line of sight. He takes extra damage if you can score direct hits on the orb on his back, but it may not always be feasible.
It is recommended that you maintain your distance because the warden’s sword does massive damage, often instantly destroying vehicles.
Hope this helps.