Astral Voice

The 2-piece effect unlocks once you equip 2 discs from the same set (usually a base stat buff); the 4-piece effect unlocks with 4 discs from the same set (usually stronger, with its own trigger condition — read the exact text above before committing). Since every agent only has 6 disc slots total, you always pick one of two splits: three different 2-piece sets, or one main 4-piece set plus one secondary 2-piece set.

The "who should use this" list below is pulled live from each character's build data: it shows whether this set is used as the 4-piece main pick or the 2-piece secondary pick, plus which other set it's paired with — so the list updates automatically whenever the meta does, it isn't hand-picked. The main stat on the first 3 slots (HP/ATK/DEF) is always fixed no matter the set; only slots 4-5-6 are yours to choose based on role (Crit Rate/Crit DMG for standard DPS, Anomaly Proficiency for Anomaly teams, Impact for Stun-role agents). See the full 6-slot mechanic and the complete set table on the Drive Discs page, or check terms in the ZZZ Glossary.