Guide
How the kit works
Start with Special Attack: Drive Suppression while above 25% HP. It costs 16% of Max HP and gives 90% CRIT DMG for 45 seconds through Core Passive: Knight's Resolve. If an enemy attacks shortly after activation, Billy blocks the hit, gains 5 Determination and immediately moves into EX Special Attack: Cool Wheelie (Special). A hit from Cool Wheelie restores another 8 Determination.
During the ride, use Dodge: Through the Galaxy to drift. A Perfect Dodge triggers Dodge Counter: Afterfire Spin, followed by Cool Wheelie. The ride also ends in Cool Wheelie when its maximum duration is reached.
After Cool Wheelie, use EX Special Attack: Rocking Footwork (Special) if you have enough Adrenaline. It restores 15% of Max HP. EX Special Attack: High-Traction Wheels (Special) is another Adrenaline option and restores 30% of Max HP.
Basic Attack: Knight's Technique restores a small amount of HP on hit. Press Special during its fourth hit to use Drive Suppression with half the HP cost. A Perfect Dodge into Dodge Counter: Duel King restores 10% Max HP on hit and can lead into that fourth Basic Attack hit.
At 100 Determination, hold Basic for Basic Attack: Full-Throttle Starlight, which consumes 100 Determination. Chain Attack: Knight's Swagger grants 15 Determination on activation. Use Ultimate: Starlight Knight Flying Kick when Decibel Rating is at Maximum. Billy is invulnerable during these three attacks.
Build and why
Use four pieces of Yunkui Tales. Its two-piece bonus gives 10% HP, which also helps Sheer Force. EX Special Attacks, Chain Attacks and Ultimates build stacks of CRIT Rate; at three stacks, the set also gives 10% Sheer DMG.
For the two remaining slots, Woodpecker Electro gives 8% CRIT Rate. White Water Ballad is another option with 10% Physical DMG, while Branch & Blade Song gives 16% CRIT DMG. Billy's Rupture specialty does not meet the Attack condition on the four-piece White Water Ballad effect.
On disc 4, choose CRIT Rate or CRIT DMG. On disc 5, use Physical DMG Bonus or Percent HP; use Percent HP on disc 6. For substats, look for CRIT Rate first, then CRIT DMG and Percent HP.
Starlight Rider Faceplate is the first weapon choice: it gives 20% CRIT Rate, and Special Attacks build up to two stacks of Physical Sheer DMG. Qingming Birdcage is next for its 20% CRIT Rate, though its Ether bonuses do not increase Billy's Physical DMG. Cauldron of Clarity is another option: EX Special Attacks build DMG stacks, with CRIT Rate at three stacks.
Leveling priority
Follow the game's order: Core Passive first, then Special Attack, Basic Attack, Chain Attack, Dodge and Assist. The Core Passive governs Sheer Force and the HP and Determination mechanics. Special Attack comes next because the motorcycle attacks are a regular part of his field time.
For maximum ascension, you need 800 000 Denny, 4 Basic Rupture Certification Seals, 32 Advanced Rupture Certification Seals and 30 Arbiter Certification Seals.
To max all skills, gather 2 905 000 Denny, 25 Basic Physical Chips, 75 Advanced Physical Chips, 250 Specialized Physical Chips, 5 Hamster Cage Passes, 9 Clouded Crystalline Substances and 60 Higher Dimensional Data: Bloodstained Miasma Feather.
Mindscapes worth it
Heroic Entrance is the standout upgrade. It gives Billy another 60 Adrenaline on entering the battlefield, and an EX Special Attack hit makes his DMG ignore 18% Physical RES for 45 seconds.
Wasteland Automaton is a good next upgrade to consider. It raises the DMG of Basic Attack: Full-Throttle Starlight, EX Special Attack: Cool Wheelie (Special) and Ultimate: Starlight Knight Flying Kick by 50%. It also introduces Turbocharged, which lets Special Attack: Drive Suppression move straight into Cool Wheelie and raises that hit's CRIT DMG.
Starlight Knight is worth considering for its extra Sheer DMG and the additional Physical DMG it adds to the final hit of Full-Throttle Starlight or the Ultimate when stacks are consumed. Knight's Chivalry and Radiant Armaments raise skill levels; Flames of Justice adds CRIT DMG and off-field HP recovery. If you stop at M1, you can leave the later upgrades alone.
Teams
Bring at least one Stun, Defense or Support teammate to activate Additional Ability: Blazing Starlight. Hits from EX Special Attack: Cool Wheelie (Special), the fourth Basic Attack hit, a Chain Attack or an Ultimate each grant one Starlight stack per skill use. The maximum is two, and each stack increases the DMG of Chain Attacks, Ultimates, EX Special Attacks and Basic Attack: Full-Throttle Starlight by 20%.
A Stun teammate is a good option for setting up damage windows; Defense or Support can also satisfy the passive's condition. Billy brings Physical Sheer DMG and can parry for Daze with Defensive Assist: Hero's Entrance. His passive does not require a particular teammate element.
Common mistakes
Do not let HP management catch you out. Special Attack: Drive Suppression needs more than 25% HP, so use Billy's recovery tools before he gets stuck below that threshold. Its reduced cost after the fourth Basic Attack hit is useful when HP is tight.
Do not ignore Determination or spend too long waiting at the cap of 120. Basic Attack: Full-Throttle Starlight costs 100, so use it when you have a suitable opening. Also check your CRIT Rate: Billy gets 90% CRIT DMG from his Core Passive after using Drive Suppression, but he still needs critical hits to benefit from it.
