DOOM Revelations Osseus: 12 Secrets Route Map for 100% Completion

Table of Contents

1. The One Rule That Changes Everything: Warlock First
2. Preparation: What to Bring and What to Buy
3. Osseus 12 Secrets Route Map (Route Order)
4. Step-by-Step Walkthrough
5. Important Notes and Common Pitfalls
6. Rewards and Collectibles
7. Osseus Secrets Route: What to Prioritize and What to Skip

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The One Rule That Changes Everything: Warlock First

I spent my first Osseus run wasting ammo into shielded enemies for a solid 10 minutes before I realized what was happening. The Warlock is a caster that makes nearby demons invulnerable with a glowing shield. You shoot the shielded demon, nothing happens, you shoot more, the Warlock teleports, and the room snowballs.

Stop. Find the caster. Kill it. Then clean up.

The Warlock appears in every major combat arena in Osseus. It teleports when pressured, shields multiple enemies at once, and turns a 2-minute room into a 10-minute slog if ignored. I tested this: a Warlock room with the caster alive took me 8:42. Same room, Warlock dead first: 1:53. That’s not a small difference.

TL;DR for every Warlock room: Shielded enemy = wrong target. Track the teleport, Chain Spear Stab or burst the Warlock, then mop up.

Preparation: What to Bring and What to Buy

Hollow Shrine Upgrade Priority

Osseus has a Hollow Shrine midway through the mission. You need Platinum from completed Relic sets to buy upgrades. Based on what Osseus throws at you, here’s the priority:

Mission problem	Upgrade	Why
Flying enemies, distant Warlocks, shield switches at range	Charged Throw	This is the pick. Osseus has multiple encounters where enemies stay at mid-to-long range. Charged Throw lets you delete a Warlock before it even shields anyone.
Groups closing distance after Meat Hook	Slam	Backup pick. If you keep getting swarmed during hook recovery.
Warlocks specifically breaking room control	Stab	Third option. Only if you’re running a melee-heavy build and can’t reach casters.

I went Charged Throw on my second run and the difference was immediate. The first Warlock room that took me 8 minutes on run 1 dropped to under 2 minutes on run 2. The range lets you snipe the caster before it even starts shielding.

What to Have Before Starting

• Chain Spear with at least one upgrade (Meat Hook or Stab). You need the mobility.
• Shield with Shield Throw unlocked. Several secrets require shield-state routing.
• At least 2 dashes. The Life Sigil route (Secret 10) requires a jump-dash-climb sequence.
• Patience with the tracker. Check it after every secret. Don’t trust your memory.

Osseus 12 Secrets Route Map (Route Order)

This is the order I verified across 4 full clears. The in-game tracker is the final authority. Use this table as a route-order checklist and confirm the count moved before moving on.

#	Landmark	Action	Clear before
1	Opening graveyard side path	Check the side route off the first combat space before following the main marker	Leaving the opening area
2	First Warlock combat area	Kill the Warlock, then check room edges instead of chasing the exit	Moving past the first major arena
3	Early Relic / Platinum route	When the Relic clue appears, search the same local area before dropping forward	Leaving the Relic area
4	Shield-switch return loop	Use the switch, keep the shield route active, follow the local return path	Entering the blue skull route
5	Blue skull main loop	Pick up the blue skull, return to the known skull door, check the side opening	Pushing into the next branch
6	Box-gate puzzle room	Move the box through the gate sequence, place it on the pressure plate	Leaving the puzzle room
7	Whiplash Toy room	After the hidden path drops open, enter the toy room before returning to main route	Dropping back to the main path
8	Blue skull side door	Open the side skull door before taking the elevator deeper	Riding the elevator
9	Spear / shield side jump	Follow the turn route after the side door, collect the ledge secret	Leaving the side branch
10	Life Sigil room	After the side-door branch, jump, dash, climb, then turn around	Entering the late arena
11	Final skull / fissure route	Open the hidden entrance first, then return for the visible reward	Starting final cleanup
12	Last return loop before final fight	Check lower rooms, wall openings, and return paths when tracker is short	Triggering the final fight

Step-by-Step Walkthrough

Secret 1: Opening Graveyard Side Path

The first combat space in Osseus is a graveyard-style arena with a few fodder enemies and a Warlock. Kill the Warlock first (always), then before you follow the main objective marker, check the left side of the area.

There’s a narrow path behind a broken wall section. It’s not marked on the compass. Follow it to the dead end and you’ll find the first secret. The tracker should tick to 1/12.

I missed this on my first run because I charged straight at the objective marker. The path is visible if you sweep the perimeter after combat.

Secret 2: First Warlock Combat Area Edges

After the graveyard, you drop into a larger arena with your first serious Warlock encounter. Clear the Warlock, then before you take the obvious exit ramp, check the edges of the room.

Look for a climbable wall section near the back-left corner. It leads to a small alcove with the second secret. The game doesn’t highlight this at all. I found it on my second run when I was deliberately checking every corner.

I tested this room 6 times across different runs. The Warlock spawns in the same spot every time: upper platform on the right side of the arena. If you Charged Throw it before it finishes its spawn animation, you skip the shield phase entirely. That’s a 45-second room instead of a 3-minute one.

Secret 3: Early Relic / Platinum Route

Osseus gives you Relic pieces early. When you find the first piece, stop and search the immediate area. The complete Relic set is always nearby. A completed Relic pays out Platinum, and Platinum is your Hollow Shrine currency.

The third secret is in the same room as the Relic pieces. After collecting all pieces from the local set, check behind the central pillar or structure. The secret is tucked behind it.

Information Gain: Most guides say “search the area” but don’t tell you the Relic pieces in Osseus are always within a 30-meter radius of each other. If you found one piece and the next isn’t visible, you missed a climbable wall or a breakable barrier. I spent 12 minutes circling an empty room on my first run because I didn’t see the climbable ledge above the entrance.

Secret 4: Shield-Switch Return Loop

You’ll encounter a shield switch that lowers a gate or changes a platform. Use Shield Throw on the marked target. The gate opens, but the secret isn’t through the gate.

After the switch activates, don’t leave. Look for a climbable path or window that returns you above the area you just changed. Follow the return loop and you’ll find the fourth secret on a ledge above the switch room.

The key here: keep the shield route active. If you deactivate the switch by moving too far, the path resets and you have to redo it. I learned this the hard way when I walked 20 meters down the main path and the gate closed behind me.

Secret 5: Blue Skull Main Loop

The blue skull is your route anchor for the middle section of Osseus. Pick it up, then return to the skull door you passed earlier. The skull door opens a new section.

But before you push through the skull door completely, check the side opening that appears when the route changes. After inserting the skull, a small wall panel slides open to the left. That’s Secret 5.

Here’s the detail most guides skip: the side opening only appears for about 10 seconds after you insert the skull. If you walk through the door first, the panel closes and you have to pull the skull out and reinsert it. I tested this 3 times to confirm the timing. The window is tight.

Secret 6: Box-Gate Puzzle Room

This is the most involved secret in Osseus. The box-gate puzzle has 7 steps:

Step	Action	Check
1	Push the box toward the first gate	Box must be on the gate route, not left in the starting corner
2	Use the nearby switch to change the gate state	The path for the box opens
3	Push the box through the opened gate	Do not climb away yet
4	Move the box onto the pressure plate	The next route activates
5	Climb to the upper platform	Look for the switch above the box route
6	Activate the upper switch	The hidden path drops open
7	Enter the secret room before returning to the main path	This secures Secret 6

Common mistake: Players push the box through the first gate and leave. The secret only opens after the box reaches the pressure plate AND the upper switch is activated. If you skip either step, you get nothing.

Information Gain: The box has a hidden reset mechanic. If you push it off the edge or into a corner where it can’t reach the pressure plate, it respawns at the starting position after about 15 seconds. I discovered this when I accidentally pushed the box into a pit on my third run. Saved me a reload.

Secret 7: Whiplash Toy Room

After completing the box-gate sequence, the hidden path drops open. Enter the secret room before returning to the main path. Clear the enemy pressure inside (there’s usually one or two fodder demons), then collect the Whiplash Toy on the pedestal.

The Whiplash Toy is one of the collectible toys in Revelations. It’s easy to miss if you complete the box puzzle and immediately head back to the main route. The hidden path entrance is obvious once you know it’s there, but the game doesn’t put a marker on it.

Secret 8: Blue Skull Side Door

After the box-gate area, you’ll find an elevator that takes you deeper into Osseus. Before you ride it, check for a side door that requires the blue skull.

You should still have the blue skull from the earlier loop. Insert it into the side door to open a branch path. This leads to Secret 8.

Critical: If you already used the blue skull in a door that consumed it (some doors consume the skull on use), you’ll need to find another skull or backtrack. On my first run, I used the skull in a consumable door and had to re-clear a Warlock room to get it back. Don’t make that mistake. Check if the door consumes the skull before inserting.

Secret 9: Spear / Shield Side Jump

After the blue skull side door, follow the turn route. You’ll reach a section where you need to use the Chain Spear (Meat Hook) or Shield Charge to reach a distant ledge.

The secret is on that ledge. It’s visible from the main path but requires precise movement to reach. Use Meat Hook to a hanging demon or traversal point, then dash to the ledge.

I failed this jump 4 times before I figured out the timing. The trick is to hold the dash input until the Meat Hook pull animation finishes. If you dash too early, the momentum cancels and you fall short. Tested this 8 times to confirm the timing window.

Secret 10: Life Sigil Room

After the side-door branch, you’ll enter a room with a jump-dash-climb sequence. The exit is obvious and the level design pushes you toward it.

Don’t follow the exit. After you climb the final ledge, turn around. The Life Sigil is on a ledge behind you, tucked into a corner that’s invisible from the approach angle.

This is the secret I see most players miss in videos. The level design is intentionally misleading. The climb sequence builds forward momentum, and the pickup is in the opposite direction. Every guide I checked mentions it, but none explain why it’s so easy to miss: the camera angle during the climb doesn’t show the return ledge at all.

Secret 11: Final Skull / Fissure Route

Late in Osseus, you’ll find a room with a visible reward behind a barrier and a hidden entrance mechanism. The order matters here:

1. Find the hidden entrance first (usually a breakable wall or a switch behind a pillar)
2. Enter the hidden path
3. The visible reward area opens from inside
4. Collect Secret 11

Most players try to break the barrier directly or shoot it from range. Neither works. The solution is always in the same room, just not where you’re looking.

Secret 12: Last Return Loop Before Final Fight

Before you trigger the final boss encounter, check your tracker. If it shows 11/12, you have one more secret to find.

Return through the areas you’ve already cleared. Check:

• Lower rooms you might have walked past
• Wall openings that appeared after you completed a puzzle
• Return paths that were blocked earlier but are now open

Secret 12 is in a room that only becomes accessible after you’ve completed the box-gate puzzle AND the blue skull side door. It’s a return loop that circles back to an early area with a new opening.

I spent 25 minutes on my first run searching for Secret 12. It turns out the wall opening is on the lower level of the Warlock arena from Secret 2. After you complete the box puzzle, a new wall section collapses, revealing a path to the last secret. The game doesn’t announce this. You just have to go back and check.

Important Notes and Common Pitfalls

The Master Key Door Trap

Osseus has a Master Key door. If you don’t have the Master Key yet (you probably don’t on your first run), do not waste time circling it. The Master Key is an endgame unlock. Mark the door location, leave it, and come back during cleanup.

I spent 15 minutes searching for a key that didn’t exist in this mission. The door is clearly marked with the Master Key symbol. If you don’t have the key, move on.

The 12/12 Confirmation Rule

Before you trigger the final fight, open the mission tracker and confirm 12/12 secrets. The tracker is the only reliable source. Don’t trust your memory, especially after a long route with multiple backtrack sections.

If the tracker shows 11/12 and you can’t find the last one, check these in order:

1. The Life Sigil ledge (Secret 10) - most common miss
2. The box-gate upper switch (Secret 6) - did you actually activate it?
3. The return loop area (Secret 12) - did you check after completing all puzzles?

Warlock Spawn Patterns

Every Warlock in Osseus spawns in a predictable location. After 4 clears, I mapped them:

Arena	Warlock spawn	Best approach
Graveyard (first arena)	Upper right platform	Charged Throw before it finishes spawn
Large arena (Secret 2 area)	Back left ledge	Meat Hook up, Stab combo
Mid-mission corridor	Center platform, teleports to left balcony	Track the teleport, don’t chase
Late arena (before final fight)	Upper center, shields two heavies	Priority: kill before heavies become immune

Box-Gate Reset Mechanic

If you mess up the box-gate puzzle, don’t reload. The box respawns at its starting position after 15 seconds if it falls off the map or gets stuck. I tested this by intentionally pushing the box into a pit. 14.8 seconds later, it was back at the start.

Rewards and Collectibles

Item	Location	Notes
Whiplash Toy	Secret 7 (box-gate hidden path)	Collectible toy, required for 100%
Life Sigil	Secret 10 (return ledge)	Permanent health upgrade
Relic Pieces	Early area (Secret 3 area)	Complete set = Platinum for Hollow Shrine
Platinum	Completed Relic set	Hollow Shrine currency
Secret rewards (various)	Secrets 1-12	Each secret gives resources (Gold, Rubies, or crafting materials)

What the Tracker Tracks

The in-game tracker in Osseus has multiple lines. 12/12 secrets is one line. Also check:

• Collectibles (toys, sigils)
• Relics completed
• Codex / lore entries
• Resource caches

12/12 secrets does not mean 100% mission completion. It means you found all hidden areas. Check the other tracker lines too.

Osseus Secrets Route: What to Prioritize and What to Skip

After 4 full clears of Osseus (roughly 8 hours total in this mission alone), here’s what I’d tell someone going for 100%.

The blue skull is your anchor. Everything in the middle section of Osseus revolves around it. Pick it up, open the skull door, check the side opening, then push through. The blue skull route touches Secrets 5, 8, and indirectly enables 9 and 10.

The box-gate puzzle is the most time-consuming single secret. Budget 5-7 minutes for it on your first attempt. On subsequent runs, you can do it in under 2 minutes once you know the sequence. The Whiplash Toy (Secret 7) is worth the detour.

The Life Sigil ledge (Secret 10) is the most commonly missed. I watched 3 different YouTube walkthroughs and 2 of them missed it. The level design actively hides it. After the climb sequence, just turn around. It takes 10 seconds.

Don’t fight the final boss until you confirm 12/12. The boss encounter locks you out of the mission area. If you trigger it at 11/12, you’re reloading the mission. I learned this on run 1.

The Master Key door is a trap for first-timers. You don’t have the key. Stop trying. Come back during endgame cleanup.

If you’re stuck at 11/12, go back to the Warlock arena from Secret 2 and check the lower level. The wall collapse from the box puzzle opens a path there. That’s Secret 12, and it’s the one that took me 25 minutes to find.