Himeko Nova functions at E0 because her Talent, shared Assist Skill, and two Companion Protocols are already complete. Eidolons improve the command economy, the reward from each protocol, and the scale of her Ultimate. For most accounts, the key question is not whether every Eidolon adds damage. It is whether the next copy changes how often the team gets a free Assist Skill or makes an existing Verdict or Decimation roster noticeably smoother. E1 and E2 are the most direct early upgrades, while E6 is a full investment tier.
E1: lower the protocol threshold
E1, That Which We Stride Is the Trailblaze, adds one Assist Skill use from Nova’s Talent. It also reduces Verdict’s required allied Ultimate count by one and reduces Decimation’s required stack count by three. When Nova herself triggers Assist Skill, she gains one additional damage instance. This is a quality-of-rotation Eidolon first and a damage Eidolon second.
The benefit is easy to feel in both branches. Verdict reaches its free command earlier because the team needs fewer allied Ultimates. Decimation reaches the free command at six stacks rather than nine, which is meaningful in encounters with fewer targets or lower hit frequency. The extra Assist Skill capacity also gives the player more room to use the command before Nova’s next Skill reset.
For an account that already enjoys Nova’s E0 loop, E1 is the clean first stopping point. It does not ask for a different relic set or an unfamiliar team. It makes the selected protocol happen more often. That is more valuable than a small isolated multiplier because the protocol controls the distinctive part of her kit.
E2: the major command upgrade
E2, The Colors We Never Strike, raises the Assist Skill use cap to two. It raises Ultimate and Assist Skill damage to 130% of their normal values. During Navigator’s Semaphore, the party also immediately recovers one Assist Skill use at each turn start. It extends the Extra Turn support from Hark! The Express’s Pulse Roars to non-Trailblaze Companion characters when they use Assist Skill.
This is the strongest early Eidolon because it improves capacity, recovery, damage, and team flexibility at once. Two stored commands reduce the risk that a turn order issue wastes part of the field. Extra recovery during Semaphore means Nova can keep the command economy moving without pressing Skill only for a refill. The 30% improvement to Ultimate and Assist Skill reaches the exact actions built around her signature light cone and relic set.
Players deciding between E1 and E2 should separate two goals. E1 makes protocol triggers arrive sooner. E2 makes the full engine larger and more forgiving. If the budget allows only one early copy, E1 is already a defensible stopping point. If the account is committed to Nova as a long-term carry, E2 is the first upgrade that changes the practical ceiling of every rotation.
E3 and E5: trace level copies
E3, We Who Are Starborn Muse Starward, raises Ultimate by two levels up to level 15 and Basic ATK by one level up to level 10. The additional Ultimate scaling is useful because Nova’s six beams, pulse, and Final Hits are a major source of her personal damage. The Basic ATK level is a smaller part of the value. Treat E3 as a progression copy on the way to another target, not as a required endpoint for a normal account.
E5, To Cross the Cosmos and Beyond, raises Skill and Talent by two levels each, again with a level 15 maximum. Skill gains improve the team damage bonus and Talent gains improve Nova’s RES PEN and Critical Damage. These are good multipliers because they are attached to core actions, but they do not create a new command rule. The practical decision remains the same: take them when pursuing later Eidolons, not because an E0 or E2 account needs them to function.
Trace Eidolons can look large on a detail page because they touch multiple numbers. In actual play, Nova still needs protocol timing, Critical Rate, and a team with a real trigger. Gear and team coherence usually improve an early account more than skipping those foundations for a trace-level copy.
E4: a team-wide penetration effect
E4, Let No Skyward Hand Stay Unheld, changes the Talent-triggered All-Type RES PEN bonus so that it applies to the entire party. Nova herself receives an additional personal RES PEN increase. The exact added personal percentage should not be treated as a build target here because the published effect text does not provide a reliable final number for it.
The important gameplay result is clear: E4 turns a personal penetration feature into a party payoff. That aligns especially well with Decimation, where the team already values a broad Critical Damage effect, and it still improves Verdict’s supporting allies. It does not replace the need to select one protocol. It magnifies the team that has already been assembled around one.
For a player who is not chasing high Eidolons, E4 is a luxury step. E1 and E2 improve the command engine earlier and are easier to justify. E4 belongs to a deeper investment plan where the player wants Nova to increase the entire party’s damage as well as her own.
E6: complete the premium build
E6, Ours Is the Oath to Sail Starward, grants 20% Fire RES PEN, raises Source Energy’s cap to six, increases Assist Skill damage by 75% when an ally uses or triggers it, and gives Nova one Source Energy from those events. Hyperluminal Particle Beam also grants an additional Source Energy. When Orbital Annihilation Pulse is fired with at least six Source Energy, it adds one extra AoE Fire hit worth 160% of Nova’s ATK.
This is a full-investment Eidolon. It expands the resource cap, accelerates the Ultimate’s Source Energy flow, increases Assist Skill damage sharply, and adds a new high-energy pulse payoff. It makes sense only for an account that already has the signature light cone, a finished protocol team, and enough relic quality to convert the extra hits into reliable Critical damage.
Do not use E6 as a benchmark for whether Nova is good. E0 contains her identity. E1 and E2 are the sensible early priorities. E6 is the reward for a player who wants every part of the Starblazer loop to scale at once.
Recommended priority
For most players, stop at E0 if the goal is to access the character and build one working protocol team. Consider E1 if the roster is already ready for Verdict or Decimation and you want the free Assist Skill timing to arrive sooner. Consider E2 when Nova is a favorite carry and the account wants a larger, more forgiving command economy. E3 through E5 are intermediate progress. E6 is a premium endpoint.
This ordering is about return on actual gameplay. A copy that lets the party store, restore, or earn Assist Skill more naturally changes every wave. A trace-level copy improves numbers, but it cannot repair an account that has not selected a protocol or has neglected Critical Rate. Finish the team and the build before turning Eidolons into the next resource goal.