ZZZ Shiyu Defense — Unlock, Reset & How It Differs From Deadly Assault | Zenless Zone Zero

You need to reach Inter-Knot Level 35, get promoted to "Certified Proxy," then finish the mode's intro commission. That commission is tied to the main story, so simply pushing the campaign gets you there. Once unlocked, you enter Shiyu Defense from the endgame combat menu.

Note: the old requirement (Level 20) was changed in patch 2.5, so it is now Level 35.

Shiyu Defense splits into three areas:

• Stable Node and Disputed Node: unlocked as you progress and never reset. These are one-time first-clear rewards worth a few thousand Polychrome in total — roughly 3,000 and 1,600 per game8. Note that Disputed Node's early stages can be cleared with a single team; only from stage 3 onward are two teams required.
• Critical Node: resets on a schedule and is your steady, repeatable Polychrome source. This is the part players farm each cycle.

New players should clear Stable and Disputed first for the one-time Polychrome, then tackle Critical Node.

The Critical Node has several stages, and each one asks for two teams — that's 6 agents and 2 Bangboo. Your job is to wipe out every enemy inside a time limit; the faster you clear, the higher your grade. Each stage has its own target time and three reward tiers: B for clearing, A for beating the target time, and S for clearing comfortably under it — aim for S on every stage to collect the full Polychrome. Because you field two teams, you need a wide roster, not all your gear on one squad.

Prep tip: push your Inter-Knot Level toward 50 so your agents can reach their Lv60 cap — both modes get much easier.

Reset: the Critical Node swaps its enemy layout and buffs every two weeks (on a Friday, at 04:00 server time). Each reset is a fresh Polychrome farm — up to roughly 780 Polychrome per cycle per game8 (varies by patch). Stable and Disputed do not change.

Deadly Assault is the second endgame mode. It unlocks at Inter-Knot Level 40, once Shiyu Defense is open, after you finish the "Deadly Situation" commission (talk at Scott's Outpost).

You fight three bosses, 3 minutes each, and the bosses have effectively endless HP — you don't need to kill them, you rack up points. Your score blends raw damage with clean defensive play — Perfect Assists, Chain Attacks, and the like. Rewards stack per star: each of the first six stars gives 50 Polychrome, so 6 stars caps the Polychrome at 300. But the full 720 Investigation Merits and 225,000 Denny only come at all 9 stars (3 bosses × 3 stars) — from the 7th star on there's no more Polychrome, just Merits and Denny. It resets every two weeks, swapping both bosses and buffs.

Both are endgame modes, both reset every two weeks, and both pay Polychrome — but they play very differently:

In short: Shiyu Defense tests your clear speed, while Deadly Assault tests your roster depth (three non-overlapping teams). The two modes update on alternating weeks.

New players should start with Shiyu Defense: it unlocks earlier (Level 35), lets you reuse agents so two decent teams are enough, and its Stable/Disputed Nodes hand out chunky one-time rewards. Once you have three solid non-overlapping teams, move on to Deadly Assault (Level 40) for another 300 Polychrome per cycle. Both are your top repeatable Polychrome sources for gacha — don't miss a reset.