Deadly Assault is the toughest endgame challenge in Zenless Zone Zero, and its boss lineup and buffs rotate every two weeks. The October 9 reset clears all previous progress and installs a new set of fights, letting players chase the full rewards again. This cycle leans into Ice and Wind damage, and it caps off with a single oversized boss in Adversity Mode.
Quick answer: The October 9 cycle runs Phaethon of the Scorched Horizon, Infernal Revenant, and Kusarikku in Trial Mode, with Integrated – Girtablullu as the Adversity Mode boss. The available buffs are Frigidity, Defense Crusher, and Knife Edge.
Trial Mode boss lineup for October 9
Trial Mode puts you against three separate bosses, each on its own three-minute timer and each requiring its own locked team. You pick one of the available buffs before every fight, so the choice depends on which boss you are facing and the squad you bring.
| Boss | Mode | Buff used in a cleared run |
|---|---|---|
| Phaethon of the Scorched Horizon | Trial | Frigidity |
| Infernal Revenant | Trial | Defense Crusher |
| Kusarikku | Trial | Knife Edge |
| Integrated – Girtablullu | Adversity | Frigidity |
Phaethon of the Scorched Horizon opens the rotation. It rewards sustained output with the Frigidity buff, and a strong S-rank run on this stage alone can bank more than 60,000 points.
Infernal Revenant is the second stage. The Defense Crusher buff helps push past its defenses, though its scoring ceiling in a clean run sits lower than the other two fights.
Kusarikku closes out Trial Mode. It is weak to Fire and Electric and resistant to Ice, and it works well with the Knife Edge buff. A tidy S-rank clear here adds roughly 48,000 points to your total.
How scoring and star ratings work
The goal is not to kill the bosses. They carry 30 life bars, and even top teams rarely drop them to zero inside the timer. Instead, you score Performance Points by dealing damage and by completing boss-specific tasks, such as interrupting a particular attack or breaking a barrier.
Each boss hands out up to three stars based on the points you reach, and every star unlocks a reward tier.
- B-Rank: 6,000 points
- A-Rank: 14,000 points
- S-Rank: 20,000 points for the full three stars
Clearing all three Trial stages with S-ranks produces a combined total in the 150,000 range. A run of 152,734 across the three bosses this cycle landed inside the top 4.00% of players, which gives a sense of what a fully invested, well-built roster can manage.
Each team you pick is locked to the boss you chose it for. You can reset a team if you picked wrong, but doing so wipes that stage’s progress. Rewards you already claimed stay yours.
Adversity Mode: Integrated – Girtablullu
Adversity Mode unlocks once you have made progress in Trial Mode, and it adds a single, extremely tanky boss on top of the standard lineup. The encounter this cycle is Integrated – Girtablullu, a towering, many-limbed creature set in a sci-fi arena. The stage lists recommended attributes of Wind and Ice and flags Physical as a resisted element, so Ice-leaning squads with the Frigidity buff fit the fight.
Adversity Mode is tuned to test even heavily invested rosters, and its scoring sits lower than a full Trial clear. An A-rank result of 29,776 points here earned a 2-star reward, which is a realistic target rather than a wall reserved only for the strongest accounts.
Rewards for the October 9 cycle
Clearing the stages and hitting star thresholds pays out Polychromes and investigation credits, the premium currency and upgrade materials that make Deadly Assault worth repeating every rotation. Adversity Mode layers on cosmetic prizes on top of that.
- Polychromes
- Investigation credits
- The limited-time item Starforged Sword
- The title “Crisis”
Unlock requirements and reset timing
Deadly Assault is gated behind account progress rather than paywalls. You need to reach Inter-Knot Level 40, unlock the Shiyu Defense mode, and clear the Deadly Situation commission. After that, the mode is permanently available and you can access it from Scott’s Outpost.
The mode resets every other Friday, which is why October 9 brings a fresh boss lineup and buff pool. Each reset wipes your run so you can claim the rewards again, and it swaps the bosses and buffs you face. There is no lower-difficulty version, so a roster of fully leveled agents with strong W-Engines, Disk Drives, and leveled skills is the baseline for scoring well. When the next rotation arrives, the lineup and buffs described here will change again.
