Osiris (level)/Walkthrough

Level notes

 * Osiris is a rather narrow level, so cover is a must. You don't have long sight lines here, so don't expect to easily stay back to snipe everything.
 * Forerunner weapons have been vastly improved over Halo 4's versions. Now many of them have greater range, better accuracy, and even tracking abilities.
 * The new Soldier enemies leap and teleport too fast to easily use the noob combo on them. The Boltshot is a better way to deal with them.
 * Unlike Elites but like Halo 3's Brutes, Soldiers' shields do not recharge when broken. Don't pursue one that flees when its shield is downed; he may lure you into am ambush.

Level Start

 * Locke: "Let's move. Vale, keep an ear on comms."
 * Vale (COM): "Affirmative."
 * Locke: "Buck, Tanaka, pull security."
 * Tanaka (COM): "On it."
 * Buck (COM): "Aye."

Your landing area is no worry, as the debris from the ship you were running from wipes them out immediately. But before you leave the crash site so quickly, there's an option you need to know. To your right, on a ledge above the ship's debris, is a combat knife stabbed into the snow. If you shoot or melee it, it will light on fire and change many of the weapon caches from Forerunner weapons to human weapons. There are seven hidden knives in total, and shooting them all unlocks a hidden boss fight. If you want greater weapon selection, you can shoot the knife for more. But if you'd rather complete the level the canonical way, then ignore it and move on to the first area.

The Crawler Assault

 * Locke: "Halsey and 'Mdama are holed up inside a Forerunner structure ahead. That's our target."
 * Vale (COM): "So Halsey called us."
 * Locke: "She said there was something big out there, and gave Captain Lasky coordinates to find her."
 * Vale (COM): "There must be something big."
 *  Buck (COM): "Or one hell of a trap."

Ahead of you is a small valley with a few boulders for cover and several raised platforms. In there are a few Grunts, two Jackals with shields, an Elite Storm, and numerous Crawlers attacking them. The first area is all about headshots. Use your pistol for this area and conserve your battle rifle for now.

As soon as you enter, you'll see a Jackal fighting a Crawler. Headshot him before he turns to face you, then take out any Grunts and Crawlers near him.