Lady Reines Case Files - Boss Guide: Ch11-3

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Enemy Layout

Fatal Battle 1/1
Shadow Da Vinci (Summoned)

Boss Statistics

Mnemosyne HP
Class Rider
NP Bar
NP Type
Up to 3 per turn
Heaven or Earth, Super Giant, Undead
Note Normal attacks (4 hits) and Critical attacks (3 hits) are both AoE.
Passive Sacred Lance Synchronization (Decreased Strength): Increase own Resistance by 50% against all attacks. [Permanent, Unremovable]
Special Skill Anima Umbra: Summon a [Shadow Servant] into the field at the start of the each turn if there is no [Shadow Servant] on the field.
* Not used if on the same turn as an HP bar break.
Break Felicitas Amnesia: Decrease the NP Gauge of all enemies by 50% and inflict NP Seal (1 turn) on them.
Break Requiesce Amnesia: Decrease the NP Gauge of all enemies by 50% and inflict Skill Seal (1 turn) on them.
Skill 1 Memory Defrag: Decrease the NP Gauge of an enemy by 20%.
Skill 2 Memory Override: Inflict Skill Seal on an enemy (3 turns).
Skill 3 Memory Deletion: Inflict NP Seal on an enemy (3 turns).
NP Anamnesis Overflow: Remove buffs from all enemies, then deal damage to all enemies.


  • Welcome to the final boss encounter of the Reines Case Files event, Mnemosyne! This boss can be somewhat tricky for the unprepared, although with the proper setup, the fight can be made more straightforward. This encounter can also technically be solo'd with Qin Shi Huang (see video section).
  • Mnemosyne is a Rider-class enemy with AoE-hitting normal attacks, which can help fill the party's NP Gauge more quickly, but also can make short work of any Caster Supports. Even then, Caster Supports are still useful; they just tend to be more difficult to keep on the field during this fight.
  • Mnemosyne will start with a Damage Resist +50% passive that is unremovable and permanent.
  • The boss will summon a Shadow Caster Servant as soon as they are able to, although they will not use the summoning skill on the same turn as an HP bar break. It is possible to entirely prevent the Servant from being summoned if they are stunned or HP-broken every turn. Note the shadow Servant's charge skill is a single-target Extra Attack.
  • Only Mnemosyne needs to be defeated; the Shadow Caster Servant does not have to be defeated to end the encounter.
  • First break results in a 50% NP Gauge drain and 1-turn NP Seal on the entire frontline.
  • Second break results in another 50% NP Gauge drain and 1-turn Skill Seal on the entire frontline.
  • Mnemosyne may also occasionally use skills that can either NP Seal or Skill Seal a random target for a full three turns.
  • Be wary that the boss's NP will remove buffs first before dealing damage to the entire frontline. This renders any Evade/Invincible/Guts abilities ineffective. The only alternative is to either delay the boss's NP through drain / NP Seal / stun effects, or by stacking ATK/NP Damage debuffs on the boss.

Team Recommendations

  • With the primary boss of this encounter being Rider class, ST Assassin DPS are the best choice, although Alter Ego DPS also does quite well.
  • Be wary that the Shadow Servant summoned by Mnemosyne is Caster class, which has offensive advantage over any Assassins that may be fielded. Masters can postpone the Shadow Servant's summoning by quickly breaking Mnemosyne's HP bar or stunning them on turns when their HP bar can't be broken.
  • Given the undesirable NP Seal and Skill Seal effects in this battle, Debuff Clear support is useful to bring for this fight. For this reason, Servants such as Saint Martha or BB are good choices to have in the backline so they can be swapped in with the Mystic Code: Chaldea Combat Uniform - Order Change skill and clear the DPS's debuffs on demand.
  • Having Debuff Immunity on the DPS is a good alternative, with several ST Assassins and Alter Egos providing some degree of Debuff Immunity, which arguably is most important after the first break (NP Seal effect), meaning the skill should be used when the first HP bar is expected to be broken. Li Shuwen (Assassin) and Sitonai both have Debuff Immunity and Class Advantage.
  • Having the standard NP Gauge and Damage Supports such as Zhuge Liang, Skadi, and Merlin are great choices. Reines herself also does decently well, having an event bonus and lack of defensive Class disadvantage.

Video Links

Quick Servant Suggestions

- Recommended
- May require higher NP Level, Grailing, or use of Command Codes.
ST Assassin DPS
ST Alter Ego DPS
Buff Removal Resist DPS (To survive NP Turns)
Trait Bonus DPS (Undead)
DPS with Debuff Immune / Class Advantage
Solo Servant
Debuff Clear Support (Skill)
Offensive Support
Last Man / Solo Servant
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Content Director at GamePress. Passionate about fighting games, virtual/augmented reality technology, neuroengineering, and video games in general. Classical Piano Performance, Sprite Art, and Under Night In-Birth enthusiast.