Kit out this cyborg gunslinger with the very best setup.
The best Billy build in Zenless Zone Zero is a pretty straightforward one, centred around buffing the gun-toting cyborg's crits and ability to proc the powerful physical anomaly, Assault. He might not be the game's greatest attack character, but physical is a very strong attribute for damage-dealers, and best of all, Billy is free when you start the game.
If you pre-registered and got Corin free, too, but aren't a big fan of her chainsaw, Billy might serve you better. He's got a pretty unique playstyle among other agents, focusing as he does on blasting foes at range and hitting lots of enemies at once with his chain and dash attacks.
His additional ability that buffs his ultimate damage by 50% for every chain attack he performs is also a pretty fun feature, letting you build towards a supercharged ultimate. That said, here's my best ZZZ Billy build, plus what materials you'll need to level him.
Billy is one of the simplest characters in ZZZ; a physical attack agent who focuses on dealing with enemies at range. His two most notable features are that he gains increased damage in the Crouching Shot stance—which he'll hop back into after his initial attack—and provided you keep inputting attacks he'll stay in that stance blasting at an enemy.
His additional ability also means he gains 50% increased ultimate damage whenever he performs a chain attack, stacking twice. The best Billy build focuses around buffing his crits and his anomaly mastery so he can trigger Assault more easily.
The best W-Engine for Billy is definitely the A-tier Starlight Engine Replica. This increases physical damage by 36% for eight seconds when you hit an enemy at least six meters away with a basic attack or dash attack. If you're playing Billy right, i.e as a ranged character, this buff should be very easy to keep active.
There's only one S-tier W-Engine that suits Billy right now, and that's The Brimstone. This engine increases attack by 3.5% for eight seconds when you hit enemies with a basic attack, dash attack, or dodge attack, stacking up to eight times. Considering how many opponents Billy can hit at once, this buff should be easy to keep maxed out, but personally I prefer the A-tier option for Billy.
In terms of Drive Discs, the physical-focused set, Fanged Metal, is a great choice for Billy. Two-pieces means 10% increased physical damage, while four-pieces buffs damage by 35% whenever a party member inflicts the physical anomaly Assault. For your other two, I recommend Woodpecker Electro for the 8% crit rate buff it provides so it'll be easier for Billy to land crits.
You can get Fanged Metal and Woodpecker Electro from the Fist and Gun, plus Tower and Cannon Cleanup activities respectively. You can also grab them from the Bardic Needle store on Sixth Street. Both of these unlock after you complete the Belobog commission as part of the main story.
In terms of base stats on the Drive Discs, I recommend:
The first two will work to increase Billy's damage, while anomaly mastery will speed up how quickly he can apply Assault to enemies, dealing a big chunk of damage when he does.
For random stats, you should look to build Billy's crit damage and then crit rate—the second is less of a priority since he gets it through his core skill enhancement and the Woodpecker Electro set. I'd then focus on attack, and possibly some anomaly proficiency if you can fit it, since this will buff the damage that Billy deals when he procs Assault.
Here's what you'll need to level up Billy in Zenless Zone Zero:
You can get Offense Certification Seals via the Combat Simulation activity that unlocks via the main story. You'll want to select Agent Promotion and then Attack Drill for Billy. Investigator Logs also come from here; simply select Basic Material and then Investigation Specialization instead.
You'll also need to raise your Inter-Knot reputation to gain access to higher character levels. Once you progress far enough, you can tweak what enemies you fight in Combat Simulation to create a custom reward set that'll get you exactly what you want.
