The Compiler is the pinnacle challenge for Marathon, as you need to obtain AI Subroutines from the vaults of Cryo Archive, solve a DNA puzzle, and fight a Warden sub-boss in a data corruption field, all while increasing your Security Clearance level and scavenging for Batteries. Since reaching this boss is difficult, you may want to prepare in advance so you can kill the Compiler on your first attempt. This guide will provide all the mechanics you need to learn in order to get that Contraband loot.
Best DPS Loadout
Before facing off the boss, the best weapons you can bring are the Bully SMG, Volt Thrower, and Retaliator LMG. Equip a magazine mod with the highest ammo capacity to keep DPSing the Compiler without reloading. This is also important for shooting down the green orbs that will come towards you because they can one-shot your shields and inflict the EMP status.
For grenades, the EMP Grenade is extremely important for this boss since it can reduce the number of incoming projectiles it can fire at you. Throwing these during the DPS phase will increase your DPS uptime, so always pack a good amount before you challenge the boss. You can also bring some Ammo Crates since your crew will be chewing through your ammo reserves for the fight.
As for the best team comp, two Destroyers and one Triage is ideal if you want to focus on just sheer DPS. Destroyer’s Search and Destroy ability adds an extra layer of damage when focus firing and works extremely well with full auto guns. Triage provides that extra amount of healing to cut down on med item usage, and an instant revive in case regular rezzing gets too risky.
Lastly, bring Energy Amps and Self Revive Kits to decrease your ultimate cooldown for DPS and stay alive longer without taking a player out of a fight for rezzing.
DPS Mechanic
The Compiler will be invulnerable when you start the fight. In order to drop its shields, you must activate a terminal displaying any symbol. Once that terminal is activated, you must then find two other terminals with the exact same symbol. These terminals cannot be interacted with until you shoot the green panels on the left and right walls of the arena, as this disables the ice field on the floor.
Once you activate three terminals of matching symbols, a green energy field will appear near the center of the arena. You and your team must stand in the green energy and shoot the glowing orb at the Compiler. Dealing enough damage to the Compiler causes it to remove its cloak and expose its real body, allowing you to DPS the boss.
While it's vulnerable, multiple green projectiles will start coming towards you. During this phase, back away from the boss so you have space and time to shoot the projectiles while DPSing it. Throwing EMP Grenades at it extends your damage phase for a short time, so apply these generously at the Compiler if you have them.
