My Brother's Keeper

What you need before you start

Three things must be done before the quest will accept a single input. None of them are part of the quest itself, but skipping one costs you a round or worse.

• One upgraded elemental bow per player. Solo in a public match that means a single bow — any of the four. In a private or custom match all four bows are required no matter how many players are in the game, which catches a lot of people out.
• The Ragnarok DG-4, built. You cannot enter the boss arena without it, and it is the only thing that damages the boss.
• The Death Ray activated at least once. The time-travel step cannot proceed otherwise, and it also gates one of the Ragnarok parts.

Setup: power, Pack-a-Punch, Ragnarok

Power is in the Armory, on the wall beside the generators. From the tram station at spawn you are buying your way up through the courtyard, across the bridge and through the bedroom to reach it. Jugger-Nog sits just past the gate in the underground tunnel and needs power on.

Pack-a-Punch is not in one place. Three teleporter pads each hold a piece of the machine — one on the Bastion near the Death Ray, one in the Undercroft, and one on the Rocket Platform, which you reach through the Undercroft teleporter for 500 points. Interact at each pad to send its piece away. Order does not matter; the machine assembles at whichever pad you activate last, and afterwards it rotates between the three locations between rounds.

The Ragnarok DG-4 takes three parts and is built at the workbench beside the pyramid in the Undercroft. The first part drops from the first Panzersoldat, which arrives on round 12. The second floats above the Bastion once the Death Ray has been used, and has to be grabbed mid-flight from a Wundersphere — press interact while you are still in the air. The third is the awkward one: during a rocket test, pull the lever at the bottom of the left staircase behind the rocket, sprint into the tunnel before the test kills you, then wait until all three lights on the console are solid green and interact. Solo, you will usually need a second test to get both halves done.

Step 1 — Charge the teleporter beacons

Put your upgraded bow back in its box and collect the plain Wrath of the Ancients from the Family Crypt — this step wants the base bow specifically. In the Undercroft teleporter room, shoot each of the electrified rods on top of the teleporter until the tip glows faintly orange.

Confirmation: the orange glow fades and a Margwa growl plays. Then swap back to your upgraded bow, because the next step is timed and wants the upgraded one.

Step 2 — The wisps

This is the step that fails people. Eight objects around the map can spark. Only one sparks at a time, and you must shoot four in sequence with an upgraded bow. Which objects are used is randomised per game, and the same object never repeats within a sequence.

Each successful shot stops the object sparking and is followed a second or two later by a Margwa growl. After the fourth, a distinct cue plays. Once you have attempted this step, it re-arms at the start of every round, so a failed run only costs you the round.

Step 3 — Travelling to the past

The bottom light on the teleporter turns purple. In co-op every player has to step in together. You arrive in the past laboratory with your weapons disabled while Groph talks to Richtofen. There are three things to do here:

1. Hold use on the large glowing blue canister in the left corner near Groph. This is the Soul Canister and you need it much later, at the MPD.
2. Hold use on the small fuses on the wooden box in the corner to the right of the teleporter.
3. Memorise the three symbols on the safe, top to bottom, shown as Groph locks it. There are four possible symbols: a lightning bolt, a rectangle with a half-circle, a circle with dots, and a diamond shape with an upward arrow. They reroll every round, so memorise them again on every trip.

Back in the present, go to the Death Ray. On the side facing the Clock Tower, insert a fuse — you will see the current start running. Then go round to the other side and pull the lever to switch it from Destroy to Protect. Now go to the terminal near the Clock Tower and enter the three safe symbols in the order you saw them, top to bottom.

That opens the safe in the past laboratory, across from the teleporter. Interacting with it gives you two large fuses and a key card from the top shelf. There is no pickup prompt and nothing appears in your inventory, so it is easy to believe you failed when you did not.

Step 4 — The memory terminals

Insert each large fuse into the two Tesla coils flanking the Death Ray — the ones with only two vertical currents running up them — then set the Death Ray back to Destroy. You do not need to fire it again.

There are two five-monitor terminals: one outside the Clock Tower and one on the Rocket Platform. Interact with either. Four symbols flash across the bottom screens and disappear; the top screen then shows them one at a time and you interact with the screen matching each. When the machine shuts down with a success cue, go and do the other terminal — same symbols, rearranged.

Failure here is cheap: you can immediately interact again and retry as many times as you like within the round. The one catch is that failing the second terminal makes you redo the first as well.

Step 5 — Sabotage the rocket

Both orbs on top of the Tesla coils are now lit. Press the green button on the back of the Death Ray. A rocket falls, destroys the Clock Tower bell and crashes into the Upper Courtyard, and Groph seals the frozen Ultimis Dempsey behind a lightning barrier that will hurt you if you touch it.

Step 6 — The Keeper and the MPD

Travel to the past a second time, which means doing the wisp step again exactly as before. Every round after your first trip opens with a Margwa growl, so a wisp is always available. In the past, hold use on the computer to the left of the Kronorium on the right-hand side of the room to insert the key card. A case near the blocked Undercroft doorway opens with a stone tablet bearing the Keeper symbol — take it and wait to return.

In the Family Crypt, place the Vril Generator in the slot on the slab below the resting knight. A ghostly Keeper appears and Hellhounds begin spawning endlessly for the rest of the step, awarding no points.

The Keeper visits four locations in a random order: the Church courtyard beside the Mystery Box spawn, beside Mule Kick, by the knight armours down the hall from the power switch, and beside Double Tap. At each one, stand in the white circle and get kills to charge the tablet. The screen edge tells you which bow it wants — blue for Storm, teal for Wolf Howl, orange for Rune Prison, purple for Demon Gate.

• Solo in a public match, all four circles accept the one bow you upgraded.
• Zombies do not need to be inside the circle — only you do. More players standing in it widens the radius.
• Hellhound kills do not count, and neither do bow melee kills.
• You can step out and come back; progress is not lost.
• At the Double Tap location the Keeper is slouched and will ignore you until you hold action on the empty square slot to its left and place the stone tablet there.

After the fourth circle the Keeper becomes solid, walks to the Undercroft, is struck by lasers where the pyramid stood, and teleports in the Moon Pyramid Device. Three of its four corners hold canisters. Place the Soul Canister you took from the past in the empty fourth corner to open it, revealing the Corrupted Keeper.

Preparing for the boss fight

The fight is long and the failure states are abrupt, so it is worth spending points before you trigger it.

• Danger Closest is the single most useful GobbleGum here. It negates the skull stuns, the Panzer shock-mine stun, and your own splash damage — which in turn makes the Ray Gun and a Pack-a-Punched MR6 excellent instead of dangerous.
• A Pack-a-Punched shotgun clears Panzersoldats quickly. Bring one.
• Mule Kick lets you carry a bow, an anti-Panzer weapon and a boss-damage weapon at once. In co-op you can split those roles instead.
• No bow does meaningful damage to the Keeper. They are there to charge the Ragnarok and to get you out of being surrounded. Storm and Rune Prison handle Panzer crowds; Wolf Howl and Demon Gate do not.
• Monkey Bombs help. Max Ammos do spawn at fixed points in the fight, but bring reserves anyway.

To start the fight, every player places their Ragnarok DG-4 in trap mode on one of the blue anti-gravity tiles. You are then teleported into the arena.

Step 7 — The Corrupted Keeper

A dark circular room with glowing blue pillars. Your Ragnarok drains to empty and then instantly refills as the fight starts; after that you recharge it with kills as normal. The Keeper has four attacks, one per bow element.

The fight runs five phases. Phases 1, 3 and 5 are the Keeper as described, with Hellhounds added in phase 3 to keep your Ragnarok charged. Phases 2 and 4 remove the Keeper and send in Panzersoldats and skeletons instead; the first Panzer you kill drops a Max Ammo. A Max Ammo in the centre of the arena marks each transition. In co-op, phase 5 also spawns a Panzersoldat every time the Keeper winds up its shockwave. A final scream and a spin means it is dead.

Step 8 — The Summoning Key

You are returned to the MPD. On one side is a glowing blue circle shaped like the Vril Generator — hold use, wait a few seconds, and pick up the Summoning Key. Carry it to the terminal outside the Clock Tower, the same one you used for the memory game, and interact. The key rises and discharges, every zombie despawns, and the ending plays: the castle rockets launch at the Moon and destroy Griffin Station, killing Groph.

The reward is all nine perks on the map, a moment of damage immunity, 2500 XP and the Frozen Freedom title. Your perk slot cap is not raised, and going down still loses them.

When something goes wrong

A note on sources

Treyarch and Activision never published a walkthrough for any of these quests, so every step above is community-derived and was cross-checked against multiple independent guides before publication. A few figures are approximations rather than datamined values — the rocket test interval (roughly five to seven minutes) and the anti-gravity interval (roughly two to four minutes) in particular. If you find a step that behaves differently on your platform, tell us.

Source: Call of Duty Wiki — Primary reference, cross-checked.