Stella Sora's hostile-depth endgame compresses every late-game system into one unforgiving rotation, so this walkthrough cuts straight to the builds, vulnerabilities, and stamina economics that actually clear runs. Ascension content in this title is a layered gauntlet of timed boss swaps, defense holds, and rotation pressure, and the Through Hostile Depths mode sits at the center of that pyramid alongside Menace Arena, A Finale Echoing, Boss Blitz, Cataclysm Survivor, and Proving Grounds. The walkthrough below is written for the Global Steam build that launched on 2026-10-19 alongside the Version 2.0 / 1st Anniversary update, and it leans on the same six-element (Aqua, Ignis, Terra, Ventus, Lux, Umbra), two-role (Vanguard, Versatile) framework the official site publishes.
Through Hostile Depths Mode and the Ascension Ladder
The hostile-depth mode is positioned above Normal / Hard / Extra Hard and below the Beyond / Chaotic ceiling, which means it is the first place where defensive tools start to matter as much as raw damage. The official difficulty ladder names six tiers in this exact order, and the game rewards squads that can absorb a hit while still converting Ultimates into meaningful burst windows.
Where Through Hostile Depths Fits Among Modes
The activity roster has grown dense enough that picking the right mode for the right goal is half the battle. The table below maps the Ascension-flavored modes to their stated purpose and their main pressure axis, all drawn from the official mode list published on the news hub and reflected in the Stella Sora on Steam for stella sora through hostile depths guide.
| Mode | Stated Purpose | Primary Pressure Axis | Notes from Official Sources |
|---|---|---|---|
| Through Hostile Depths | Layered boss + defense gauntlet | Mixed burst and sustain | Difficulty sits between Extra Hard and Ultimate |
| Menace Arena | Rotating elite ladder | Burst windows and backline swaps | Recommended for high-Authorization teams |
| A Finale Echoing | Score-chase run | Time-gated scoring | Rewards Ultimate uptime and Harmony Skill chains |
| Boss Blitz | Rapid-fire boss kills | Reset efficiency and stamina | Used to farm Defender's Medal and Star Emblem Polisher |
| Cataclysm Survivor | Defense hold | Frontline durability | Popular among squad builders testing Vanguard cores |
| Proving Grounds | Rotational trial | Role and element coverage | One of the most efficient sources of Gold Disc and Silver Disc |
Each mode reads as a separate skill check even though they share the same Trekker roster, and the Through Hostile Depths gauntlet is designed to be the most punishing because it stacks a defense phase on top of a burst phase in a single ticket.
Core Squad Shape for Hostile-Depth Tickets
A balanced three-Trekker squad should anchor a Vanguard frontline to absorb aggro, slot a Versatile midliner for off-element flex, and cap the backline with a second Versatile that can pivot into either a healer-style or a DPS-style shell depending on the published Enemy Vulnerability for the active phase. The official sources only state two roles (Vanguard and Versatile) and explicitly avoid the DPS / Support / Tank / Healer labels that other Yostar-published titles use, so any writeup that frames a Trekker as a "healer" is borrowing vocabulary the developers have not adopted.
Because the mode rotates elements, the practical rule is to bring at least two elements that appear in the current Enemy Vulnerability line, plus one off-element Trekker for the transition phase where the vulnerability swaps. Community testing reported by players shows that a same-element core plus one flex outperforms a fully rainbowed squad in this mode, which lines up with the official same-element team-building advice that appears in the version 2.0 patch notes.
Stella Sora Menace Arena Guide: Rotating Elite Rotations
The Menace Arena is the closest neighbor to Through Hostile Depths, and the two activities share a lot of muscle memory. The arena is structured as a rotating ladder of elite encounters where the Enemy Vulnerability shifts every reset, and the pressure comes from picking the right moment to commit your Ultimate so it lines up with the active weakness window.
Reading the Weekly Vulnerability Schedule
The arena publishes a two-element vulnerability at a time, and the most efficient squads pre-build one Trekker core around element A and a second core around element B so they can swap cleanly on the reset day. The table below uses the official six elements (Aqua, Ignis, Terra, Ventus, Lux, Umbra) and shows the kind of split-squad planning a serious climber should track across a normal rotation week.
| Hypothetical Reset | Active Vulnerability A | Active Vulnerability B | Frontline Recommendation |
|---|---|---|---|
| Monday | Ignis | Ventus | Ignis Vanguard, Ventus Versatile, off-element flex |
| Thursday | Umbra | Aqua | Umbra Vanguard, Aqua Versatile, Ignis flex for transition |
The exact element pairs are not publicly enumerated by the official sources, which is why a "hypothetical" framing is used here; in practice players consult the in-game notice before committing, and the in-game notice is always the final word on which two elements are boosted during a given reset.
Menace Arena Scoring Multipliers
The score screen rewards three behaviors more than any others, and they are the same three the Stella Sora leaderboard guide highlights for high-difficulty content. They are Ultimate uptime, time remaining on the clock when the final elite dies, and unbroken elemental coverage for the duration of the run. A run that scores 13 million-plus in A Finale Echoing, such as the Olympia Chaotic Umbra clear posted by the community runner referenced earlier, is built on the same trio of habits.
Boss Blitz and the Time-Attack Mindset
Boss Blitz strips the mode down to a single variable: how fast a three-Trekker squad can dispatch a sequence of bosses, with stamina as the only meaningful resource gate. The official sources have not published a drop rate table, so any claim about expected Defender's Medal yield per ticket should be treated as community-reported rather than guaranteed, but the consensus among climb-focused players is that Boss Blitz is the most stamina-efficient way to build emblem polishers and the polished emblem pool that unlocks extra affix rolls on a Runic Disc.
Recommended Boss Blitz Squad Archetypes
| Archetype | Composition | Best Use Case | Notes |
|---|---|---|---|
| Burst Window | Two Versatile, one Vanguard | Short windows of high Enemy Vulnerability | Maximizes Disc Skill and Ultimate burst in one rotation |
| Sustain Wall | One Versatile, two Vanguard | Bosses with heavy backline pressure | Trades score ceiling for consistency across longer fights |
| Flex Pivot | One of each role | Mixed element rotations | Highest reset-to-reset adaptability, lowest single-boss ceiling |
The Nazuka day-2 test referenced in the community video index showed a two-Versatile, one-Vanguard core clearing the Boss Blitz rotation faster than a frontline-heavy squad, which mirrors the same-element team logic that the version 2.0 patch notes lean on for hostile-depth content.
Stamina Economics for Boss Blitz Tickets
Daily Affairs and Quick Battle generate a small but consistent trickle of stamina tokens, and players who want to maximize emblem gains without burning a real-world timer typically chain the stamina-recovery loop with the Stella Sora vigor guide routine so that every Quick Battle consumes a refilled bar. The official sources do not list a hard stamina cap, which is why the practical advice is to spend down the bar at least once per day instead of stockpiling, because the rollover math favors a flat daily spend over an irregular burst.
A Finale Echoing: Score Chases and Harmony Skill Windows
A Finale Echoing is where the build-focused squads separate from the casual ladder, because the score screen rewards specific combat behaviors rather than raw win rate. The published scoring weights, where they appear in the community datamines, lean heavily on Ultimate chains, Disc Skill timing relative to the active Enemy Vulnerability, and the share of the clock that the squad spends inside a Harmony Skill buff window.
Harmony Skill Windows Worth Building Around
A Harmony Skill chains a short buff window onto the next Main Skill cast, and the most efficient Finale Echoing runs use the window to cover two Main Skill casts from different Trekkers so the buff is paid for once and used twice. A good rule of thumb is to plan a chain in which the buff-bearing Trekker casts first, then the off-role Trekker casts a high-multiplier Main Skill inside the window, then the Vanguard closes the chain with an Ultimate that benefits from the lingering portion of the buff.
The community reference run already mentioned, which scored 13,430,949 points on the Olympia Chaotic Umbra encounter, used exactly that chain order, and the score ceiling reflects how well the Harmony Skill window was respected rather than how much raw damage was pushed into the encounter.
When to Skip the Harmony Chain
There are two situations where a Harmony Skill chain is actively wrong, and both show up in hostile-depth content. The first is a defense phase where the squad needs the Healing-on-Ultimate behavior of a Vanguard's burst window more than a Main Skill chain. The second is an element-swap transition where the active vulnerability is about to flip, and committing to a chain locks the squad into the wrong element for the next ten to fifteen seconds.
Cataclysm Survivor and Proving Grounds: Defense and Rotation
Cataclysm Survivor and Proving Grounds are the two defense-flavored siblings of the hostile-depth roster, and they reward a very different squad shape than the burst-focused Boss Blitz or Finale Echoing ladder. The official sources describe both as a mix of defense holds and rotation swaps, and the community understanding is that the damage profile of the enemies in these modes punishes single-target frontloaded squads.
Defense Phase Squad Shape
A Cataclysm Survivor squad should run two Vanguard and one Versatile so the backline has a soft target that the enemy AI is willing to over-target. The Versatile slot is then free to use a disc set that scores a high Affix roll on healing, which is one of the most common affixes on Runic Discs, and that affix does most of the work during the long defense holds. The table below summarizes the two viable defense shapes and the situations where each wins.
| Squad Shape | Composition | Strength | Weakness |
|---|---|---|---|
| Double Vanguard | Two Vanguard, one Versatile | Long defense holds, healing affix uptime | Lower single-target ceiling on transition phases |
| Pivot Vanguard | One Vanguard, two Versatile | Faster transition, better single-target | Healing affix uptime is shorter, defense holds can leak |
For Proving Grounds the rotation is less defensive but more punishing because the mode expects the squad to clear two different role trials in a single ticket. The first trial usually tests Vanguard durability, and the second tests Versatile burst, so a Pivot Vanguard core is the safest default for the rotation because it can perform both jobs without a respec.
Affix and Runic Disc Considerations for Defense
The official Runic Disc pool currently includes sixteen named discs ranging from My Guiding Star to Fireworks, and each disc carries its own Disc Skill plus a pair of affix slots that can be rolled at the Emblem Tempering bench. Defense-oriented players should treat Star Emblem Polisher as a scarce currency and only spend it on discs that are going to live in the defense squad for at least a week, which is why the community tends to anchor the Cataclysm Survivor squad around a small pool of two or three named discs rather than a deep bench.
If the disc selection screen feels overwhelming, the existing Stella Sora disc tier list breaks the current pool into PVE, boss, and Menace Arena rankings, and it is the easiest way to shortlist two or three discs to commit polishers to before starting a long Cataclysm Survivor climb.
Cross-Mode Strategy: Building One Squad That Travels
A serious hostile-depth player eventually wants one squad that can clear Boss Blitz, A Finale Echoing, Menace Arena, and Cataclysm Survivor without a full respec, because the daily affairs routine cannot afford to feed four separate gear sets. The most efficient way to do that is to pick one element and one role as the anchor, then build a small library of Potential Presets so the Record Adjustment bench can swap the squad's role emphasis on demand.
Potential Presets as a Travel Build
The Potential and Core Potential system caps at five unassigned Potentials at a time, with each individual Note ranging from 0 to 99, which gives enough headroom to save one preset per mode without burning the Note Adjustment cap. The practical way to use that is to save a Preset for each of the four Ascension modes, plus one neutral preset for general Monolith content, and to switch presets from the main squad screen rather than rebuilding Potentials by hand.
| Preset Slot | Mode | Suggested Emphasis |
|---|---|---|
| Slot 1 | Through Hostile Depths | Mixed burst and sustain |
| Slot 2 | Menace Arena | Single-target burst |
| Slot 3 | A Finale Echoing | Harmony Skill chain alignment |
| Slot 4 | Cataclysm Survivor | Healing affix and Vanguard durability |
| Slot 5 | Boss Blitz | Disc Skill reset speed |
A squad that travels well across all four modes is one that uses an Elemental Note layout that does not change between presets, because the official sources state that the same-element team-building framework is universal across Ascension content. Changing Notes between presets would be a more invasive edit than changing Potentials, so the Notes should be the constant and the Potentials should be the variable.
Frequently Asked Questions
What is the recommended difficulty to start the Through Hostile Depths mode?
Players should clear Extra Hard cleanly on their main squad and own at least one polished Runic Disc before attempting the hostile-depth mode, because the difficulty sits between Extra Hard and Ultimate on the official ladder. Rushing in on a Normal-built squad usually ends in a wasted ticket and a depleted stamina bar.
How should I build a squad for Menace Arena when the vulnerability shifts mid-run?
The safe pattern is to anchor the squad on the currently active Enemy Vulnerability element, then carry one off-element Versatile for the transition window when the vulnerability swaps. Community testing reports that the same-element core plus one flex outperforms a fully rainbowed squad, which lines up with the official same-element team-building advice.
Is Cataclysm Survivor or Proving Grounds better for farming Defender's Medal?
Both modes drop Defender's Medal, but Boss Blitz remains the most stamina-efficient farm per official patch notes, while Cataclysm Survivor and Proving Grounds give bonus drops on rotation. The most efficient long-term farm is a Boss Blitz first, then a Cataclysm Survivor second pass for the rotation bonus, then a Proving Grounds sweep for the role-trial drops.
How many Potential Presets do I need for a hostile-depth roster?
Five Presets cover a full Ascension rotation if each preset is mapped to one mode, because the Potential system caps at five unassigned Potentials and the Note Adjustment caps at fifteen unassigned Notes. The Notes should be the constant and the Potentials the variable, which keeps the daily swap fast enough to fit inside a Quick Battle loop.
Can a single squad clear both A Finale Echoing and Cataclysm Survivor without a respec?
Yes, a Pivot Vanguard core with one Vanguard and two Versatile can clear both, because the Versatile slots cover the A Finale Echoing burst windows while the Vanguard covers the Cataclysm Survivor defense hold. The trade-off is a lower single-target ceiling on the A Finale Echoing ladder, so a player chasing the top of the scoreboard will eventually need a second specialized squad.