Three cubes carry almost every account: Resilience (reload speed), Bastion (ammo refund while firing), and Wingman (extra magazine size). Level those three first, put them on the units that shoot the most, and you have solved 90 percent of the cube question before the situational stuff even enters the conversation. Everything else is fine-tuning.
That is the shortcut. The rest of this guide is why it works, which cube each weapon type actually wants, and how to spend battery materials so you are not stuck at level 4 on the one cube your best DPS needs.
What a Harmony Cube actually is
A Harmony Cube is a fifth equipment slot. Each NIKKE wears exactly one, and it hands out a small stat plus a special effect: faster reload, more ammo, higher charge damage, and so on. The important quirk is that a cube is account-wide once leveled. You do not build one Resilience cube per unit. You level a single Resilience cube and equip that same cube on every reloader who wants it, at the level you took it to. So investment is shared, which changes how you prioritize: leveling one cube upgrades your whole roster's access to it at once.
From level 5, most cubes also grant a bit of extra elemental damage (the "strong element" bonus). That secondary skill keeps climbing all the way to 15, even after the main effect has capped. More on that in the leveling section, because it changes where the last batteries should go.
The cube roster and what each one does
Here is the current lineup and where each cube belongs. "Best on" is the default home for the cube, not a hard rule.
| Cube | Effect | Best on |
|---|---|---|
| Resilience | Reload speed, up to about 29.7% at max | Shotguns, rocket launchers, any slow reloader, and units that reload constantly |
| Bastion | Refunds ammo as you fire (a few rounds back per magazine at higher levels) | Assault rifles and miniguns, big-magazine sustained-fire DPS |
| Wingman | Increases max magazine size (additive) | High ammo-count weapons and units that want longer firing windows |
| Onslaught | Charge damage, additive (a +3.81% cube makes a 1000% charge shot hit for 1003.8%, not 1038%) | Snipers and rocket launchers built for raw damage |
| Adjutant | Charge speed, roughly 2.12% per level | Snipers and rocket launchers where charging faster matters, mostly PvP |
| Assault | Hit rate, plus strong-element damage from level 5 | SMGs and shotguns, spread weapons that miss chip damage |
| Quantum | Burst generation, up to about 4.66% | Units that need the team to reach Full Burst faster, PvP and burst-starved teams |
| Vigor | Max HP, plus strong-element damage from level 5 | Healers and buffers that scale off HP, and durable PvP units |
| Tempering | Reduces damage taken, survivability | Tanks and front-line PvP units that need to eat a nuke and live |
| Endurance | Raises DEF | Chip-damage tanking, mostly a niche PvP pick |
A couple of newer utility and relic cubes (a healing-focused cube and a support "assist" cube among them) have been rolling in on top of this core set. Their exact numbers are still shifting, so check them in-game and treat any specific figure as subject to balance changes before you sink batteries into them. The core ten above are what carry PvE progression, and they are where a growing account should spend first.
One legacy note: older guides mention a Bulwark cover-HP cube. The Max HP role has effectively moved to Vigor in the current menu, so if you are reading a two-year-old tier list, mentally map its "Bulwark for HP" advice onto Vigor and verify the cube name in your own cube list.
Cube by weapon type
Weapon class decides more than character role does. A cube that is perfect on a minigun is a waste on a sniper.
- Assault Rifles (AR): Bastion. ARs fire long strings, so ammo refunded mid-magazine means fewer reload interruptions and more time on target. Bastion's refund scales with how much you shoot, which is exactly what an AR does. Wingman is the backup if you have not leveled Bastion yet.
- Miniguns (MG): Bastion, again, with Resilience as a strong alternative. Miniguns have two dead spots: the actual reload and the spin-up wind-up. Resilience shortens the reload but not the wind-up. Bastion sidesteps both by keeping you firing, which reduces how often you eat the wind-up at all. On heavy sustained-fire MG carries, Bastion usually wins.
- Shotguns (SG): Resilience or Assault. Shotguns reload slowly and often, so cutting reload time is real uptime. Assault helps the pellets that would otherwise miss connect, adding chip damage and, from level 5, element. Pick based on whether the unit is uptime-starved or accuracy-starved. Note Bastion is weaker here: on a 9-round shotgun the refund only kicks in on a full reload and can effectively halve its value.
- SMGs: Assault. SMGs spray, and hit rate turns near-misses into damage. The level-5 elemental bonus is gravy on a strong-element matchup.
- Snipers (SR): Onslaught for damage, Adjutant for speed. Onslaught pumps the charged shot's damage and is the default for PvE bosses. Adjutant makes the charge fill faster, which matters most in PvP where firing first can decide the round. Both are additive, so do not expect either to be a huge multiplier. In a lot of PvE cases, more uptime from Resilience or Bastion quietly beats Onslaught's small charge-damage gain.
- Rocket Launchers (RL): treat like snipers. Onslaught for raw hits, Adjutant for PvP charge races, and Resilience whenever the unit's downtime is the real problem. RLs reload slowly, so Resilience is a very common pick here.
The cubes that actually matter for progression
If you are still climbing campaign and building your first solid teams, the honest priority is narrow. Resilience, Bastion, and Wingman do the heavy lifting because more uptime beats almost every fancy effect. A DPS that spends less time reloading simply does more damage across a stage, and that compounds on every unit you equip.
The charge cubes (Onslaught, Adjutant) are situational and not mandatory. They help specific sniper and RL carries, but a low-level Onslaught adds very little, so do not rush it. Quantum earns its slot on teams that struggle to reach Full Burst, which is more of an endgame and PvP concern than an early-campaign one. Vigor, Tempering, and Endurance are survivability and PvP tools; useful when you get into Arena and Solo Raid tanking, skippable while you are still learning the Burst system.
If you have not settled your five-unit shells yet, sort that first. Cubes amplify a team; they do not rescue a broken Burst rotation. Our burst team building guide covers the I-II-III chaining that every team needs, and the NIKKE tier list shows who is worth building cubes around right now.
Leveling without wasting fragments
Cubes cap at level 15, and the two halves of a cube level on different schedules:
- The main effect maxes at level 7. Everything past 7 only feeds the secondary elemental-damage skill, which keeps growing to 15.
- Leveling gets brutal after level 10, where each upgrade costs 100 batteries, and taking a single cube from 1 to 15 runs roughly 1,020 batteries total.
Batteries are cube-specific, and you get them mainly from Solo Raid (Lost Sector) clears and by buying them in the Union Shop with Union Chips from Union Raid, at a rate near 1 battery per 200 chips. Clearing all your Lost Sectors will typically fund about two levels on every cube you own, and the shop covers the rest.
The spending plan that avoids regret:
- Take your three core cubes (Resilience, Bastion, Wingman) to level 7 first. Level 7 caps the main effect, so that is where the value-per-battery is highest. This is the single best use of early materials.
- Only push past 7 on cubes your best carries genuinely use, and only when the element bonus lines up with a strong-element team. Levels 8 to 15 are a long grind for a small elemental trickle, so reserve them for your top campaign or Solo Raid DPS.
- Hold situational cubes at 7, or lower, until you actually field the unit that wants them. A level-15 Onslaught you never equip is 1,020 wasted batteries.
Because cubes are shared across the roster, one Resilience cube at level 7 quietly upgrades every reloader you own. That is why the core three come first: the return is spread across your whole account, not locked to one unit.
Putting it together
Slot by weapon, not by vibe. ARs and MGs want Bastion, slow reloaders and shotguns want Resilience, spread weapons want Assault, chargers want Onslaught or Adjutant depending on whether you care about damage or speed. Level the core three to 7 before anything else, and only chase level 15 on the carries that will really use it.
From here, cubes are one layer of a full build. Pair them with the right Overload gear rolls to squeeze out more damage, check who deserves the investment in our best NIKKEs rundown, and grab the freebies in the current NIKKE codes post to fund the battery grind a little faster.
