Billy Kid Build: W-Engines, Disc Stats & Burst Rotation

Use a weapon trigger you can maintain, balance your critical stats, and enter the damage window ready to shoot. This guide is for original A-rank Billy Kid, not Starlight - Billy. Its focus is a reproducible starter setup rather than a universal damage ranking.

W-Engines and disc main stats

Starlight Engine is the craftable option: activate its effect through a Dodge Counter or Quick Assist. Starlight Engine Replica is a different engine with a range-dependent trigger. The Brimstone is an alternative if already owned; no signature pull is required for this starter plan.

Use Woodpecker Electro (4) + Branch & Blade Song (2). Hormone Punk (2) is a practical alternative. Keep a functional existing set while collecting the replacement.

Slot	Main stat
1	HP, fixed
2	ATK, fixed
3	DEF, fixed
4	CRIT Rate or CRIT DMG
5	ATK as a starting point; compare PEN Ratio or Physical DMG in the complete build
6	ATK

Reference: Prydwen’s Billy build, checked September 20, 2026. Slot 5 depends on the rest of the loadout; a Physical main stat is not automatically strongest simply because Billy deals Physical damage.

For disc 4, inspect both critical stats rather than chasing a single impressive number. With few reliable critical hits, extra critical damage will be inconsistent. Also account for buffs that are actually present during the damage window, not every buff a different team could theoretically supply.

Disc 5: a worked stat comparison

Consider a hypothetical burst with 1,000 base ATK, 2,000 total ATK before disc 5, 70% CRIT Rate, 140% CRIT DMG and 150% applicable additive damage bonus. Keep enemy defense, PEN, buffs, substats and the attack multiplier identical.

Disc-5 change	ATK × damage-bonus factor	Result before the identical remaining factors
Add 30% ATK to base ATK	(2,000 + 300) × 2.50	5,750
Add 30% Physical DMG	2,000 × 2.80	5,600

In this deliberately simplified example, the ATK piece wins. With only 50% existing damage bonus, the same comparison becomes 3,450 versus 3,600, favoring Physical DMG. This demonstrates why the rest of the build matters; these are not observed Billy damage numbers or a complete combat simulator. PEN Ratio also depends on the enemy and other defense-related effects, so it cannot be ranked from this two-factor table.

A simple burst drill

1. Prepare Stun with Anby and support with Nicole.
2. Take Nicole’s Quick Assist into Billy to activate Starlight Engine.
3. Hold Basic to enter Crouching Shot.
4. Use Ultimate when ready, then continue attacking; fit EX into the opening when available.

Crouching Shot supports his damage. Practice it as an input sequence before adding advanced movement cancels. The visual pose alone can be misleading after some actions, so start with a short, repeatable sequence rather than trying to reproduce a speedrun.

After each attempt, ask whether the first meaningful attack landed while Nicole’s support was still useful. If you spend the opening moving toward the enemy, start the handoff from a better position. If the wrong target receives the shots, fix target selection before increasing the rotation’s length.

Upgrade the attacks you use

Prioritize Core, Chain/Ultimate and Basic for this burst plan, then improve the other skills as your rotation calls for them. Keep Agent and W-Engine progression current before hunting tiny improvements in substats.

Set a limited farming goal: one usable disc with the desired main stat, or the materials for one skill milestone. Once that goal is met, return to the encounter. This tells you whether the weakness was equipment or execution and avoids an open-ended search for perfection.

Troubleshooting low damage

Observation	Next check
Good equipment, weak opening	Engine trigger and support handoff
Plenty of attacks, few useful hits	Target, range and time spent repositioning
Strong first attempt, inconsistent repeats	Critical balance and repeatable inputs
Clean rotation still fails	Enemy resistance, stage rules and team progression

Keep the previous loadout locked until a replacement proves useful under comparable conditions. Our starter-team guide connects Billy’s damage phase with Anby’s setup and Nicole’s assist.

September 17 revision: expanded engine distinctions, replaced the old default two-piece suggestion, added all disc slots and a concrete burst drill. No new in-game benchmark is claimed.

September 20 review: added a labeled arithmetic comparison and stance-entry diagram. The cited build reference lists its last full build update as 2.8; this 3.2 editorial check does not imply fresh performance tests.