Arknights Endfield Umbral Monument Oct 5: New Stages & 1,200 Oroberyl

Arknights: Endfield Umbral Monument opens its new series, "Marked by Dark Shadows," on October 5, 2026, with four new stages and a limited-time Monumental Etching event worth 1,200 Oroberyl, and the part that catches players out is not the difficulty but the deadline. The Oroberyl is tied to a fixed two-week window that closes on October 19, rather than running to the end of the version. At the same time, Normal mode alone is enough to collect it. So the smart plan is simple: clear the four stages on Normal early, claim the Oroberyl, and treat Agony mode as optional. This preview covers the schedule, how the mode works, what the event pays, and how this fits into October's wider Oroberyl budget.

What Arrives on October 5

The new series arrives during the second half of the Dreamscape of Wind and Snow version. According to the official version notes, here is what is confirmed:

• New series: "Marked by Dark Shadows," featuring 4 stages.
• Opens: October 5, 2026.
• Limited-time event: "Monumental Etching: Shadow Marked," which begins when the series is released.
• Event window: October 5 to October 19, 2026, a fixed two weeks.
• Event rewards: include Oroberyl ×1,200 and an Advanced Progression Selection Crate I.

The two-week window is the most important detail on that list. Many other events in this version run until the next version update, which tempts players to leave them for later. Monumental Etching does not work that way, so leaving Umbral Monument until the final days of the version would mean missing the Oroberyl entirely.

Our breakdown of Dreamscape of Wind and Snow Part 2 covers the rest of the version's second half, including the other deadlines landing around the same time.

How Umbral Monument Works

Since the Oroberyl depends on clearing Umbral Monument stages, it helps to understand how the mode is structured before the new series opens.

Umbral Monument is a permanent, high-difficulty combat mode that receives new content in series. Each series contains several stages, and every stage has two difficulties:

• Normal mode: the standard version of the stage, which must be cleared first.
• Agony mode: a significantly harder version that unlocks after you clear Normal.

You only need one team of four Operators for each stage, so the mode tests how well you build and use a single squad rather than the depth of your entire roster. That makes it more approachable than its reputation suggests, especially for accounts with one strong core team.

To access the mode, earlier guides list two requirements: completing Chapter I Process II, "Paving the Way," and reaching Authority Level 30. If you have been playing since launch, you should meet both comfortably, but newer accounts should check these before October 5.

Why Normal Mode Is Enough

Understanding the two difficulties leads to the most useful fact about this event: you do not need to clear Agony to earn the Oroberyl.

Earlier this year, GRYPHLINE adjusted Umbral Monument into a permanent mode and made several changes to make it more accessible. The difficulty of certain stages was reduced, and players can now bring tacticals into stages when challenging them in Normal mode. Most importantly, during each Monumental Etching event, clearing the corresponding Umbral Monument stages in Normal mode grants the full Oroberyl rewards.

That design choice changes how you should approach the new series. The hardest difficulty does not gate your gacha currency. Agony is there for players who want the extra challenge and recognition, while the Oroberyl is available to anyone who can clear the four stages on Normal.

So if your roster is not yet built for the toughest content, there is no need to feel locked out. Bring your tacticals, use your strongest single team, and focus on clean Normal clears. You can always return to Agony later, since the mode itself is permanent.

What the Event Pays

With the requirements clear, the rewards explain why this event deserves a slot early in your October schedule.

Monumental Etching: Shadow Marked is the limited-time reward layer on top of Umbral Monument. During the event, you complete various Umbral Monument challenges and claim rewards directly from the event screen. The confirmed rewards include 1,200 Oroberyl and an Advanced Progression Selection Crate I.

Oroberyl is the currency that goes toward headhunting, so 1,200 of it is a meaningful contribution toward your next banner. The selection crate adds value on the progression side, letting you pick the materials your account needs most.

Umbral Monument also has its own permanent rewards, separate from the limited-time event. Earlier series offered items such as T-Creds, Mark of Perseverance, Advanced Cognitive Carrier, Arms INSP Set and Protohedron. Check the reward list for "Marked by Dark Shadows" in-game once it opens, since permanent rewards can vary by series.

October's Wider Oroberyl Budget

The 1,200 Oroberyl from Monumental Etching is one of several Oroberyl sources running in October, and seeing them together helps you plan your spending.

• Seven-day sign-in from October 1: worth 1,500 Oroberyl.
• "Echoing Bell of an Old City" guide event: complete missions in Suiming for 1,200 Oroberyl and a Mark of Perseverance, running until the next version update.
• Echoes of War, Season of Illusion: clear all new stages on Normal for 300 Oroberyl.
• Monumental Etching: Shadow Marked: 1,200 Oroberyl from October 5 to October 19.

Of these, Monumental Etching has the tightest deadline. The sign-in and the Suiming guide event give you more time, so the sensible order is to prioritise Umbral Monument in its first week, then return to the longer-running events afterwards.

The Echoes of War Oroberyl also comes from Normal clears, so the same strong team you use for Umbral Monument will often help there too. Our Echoes of War team guide covers team building for that mode, and our Contingency Contract breakdown explains how Endfield's other endgame challenge differs from Umbral Monument.

How to Prepare Before October 5

Because the new stages have not opened yet, the best preparation focuses on things you can control now:

1. Check access: make sure you have completed "Paving the Way" and reached Authority Level 30 so the mode is available on day one.
2. Pick your core team: choose your strongest four-Operator squad, since each stage only needs one team.
3. Stock up on tacticals: you can bring them into Normal mode, and they can make a difficult clear much smoother.
4. Clear Normal in the first week: aim to finish all four stages on Normal well before October 19, leaving time to retry if a stage gives you trouble.
5. Claim from the event screen: collect the 1,200 Oroberyl and the selection crate directly from the Monumental Etching screen before the event closes.
6. Treat Agony as optional: attempt it only after the Oroberyl is secured, since it does not affect the event's currency rewards.

The core takeaway is simple. "Marked by Dark Shadows" brings four new challenges, but the 1,200 Oroberyl attached to it only asks for Normal clears within two weeks. Clear early, claim before October 19, and save the Agony attempts for when the pressure is off.

If you would rather enter the new series with a stronger roster, you can explore trusted Arknights: Endfield Accounts, keep your stamina farming and daily missions on schedule with reliable Arknights: Endfield Hourly Services, or secure your Umbral Monument and Echoes of War clears through dependable Arknights: Endfield Boosting.

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