Mysterious Heroine XX (Alter)

“Achievement, unlocked. Heart achievement unlocked. Hehe.”

Descending from the same tangled lineage as Mysterious Heroine X, Mysterious Heroine XX (Alter) is the corrupted counterpart to the space-faring, mecha-suited idol-hero Mysterious Heroine XX. Classed as a Foreigner rather than her original's Assassin/Berserker relatives, XX Alter has a toolkit which is tailored toward a highly straightforward job: single-target Buster damage, with a built-in edge against Ruler-class, Lawful, and Good-aligned enemies.

Mysterious Heroine XX (Alter) has a compact and clearly defined kit. Quantum Armor B gives her Invincibility for 2 hits over 3 turns, alongside an Attack buff for herself, and a burst of Critical Stars for 4 turns (including the turn she activates this skill). Gravity Manipulation B is her core steroid, granting Buster Card effectiveness, Buster-specific Star Gather Rate, and Critical Strength all at once for 3 turns. Finally, Villains Terminate A rounds things out as a primarily NP Gauge - centric skill. This skill drains a point of NP Bar from every enemy on the field, and for each enemy affected by this effect, she gains 10% NP Gauge Charge. Furthermore, this skill grants her an additional fixed amount of NP Gauge and increases her NP Gain for 3 turns. Her Noble Phantasm, Genesis Flash, Disorder into Chaos, is a single-target Buster NP that increases her NP Damage by 10-30% (scaling with Overcharge) before dealing damage, grants herself temporary Special Attack bonuses against Lawful and Good enemies, deals a hefty 200% bonus against Ruler-class Servants specifically, and refunds a chunk of NP Gauge on use.

Mysterious Heroine XX (Alter) definitely has some strong points going for her, particularly a hard-hitting anti-Ruler Noble Phantasm and reliable access to a two-hit Invincibility that helps her survive long enough to deliver it. Efficient but narrow is an apt description of her skill set. All of her skills are quite straightforward, self-sufficient, and require little setup to be useful. She hits decently hard through both her Noble Phantasm, which covers a wide array of enemy Classes, and her triple Buster card deck, complemented by the Critical Stars she generates. XX (Alter) also has deceptively strong NP gain compared to most Buster Servants, thanks to her third skill and the 20% NP Gauge charge from her Noble Phantasm. She shines best when paired with Buster support Servants like Koyanskaya of Light, or more niche Servants like Van Gogh and Ashiya Douman, who can provide powerful teamwide buffs tailored to her strengths.

That said, her low support value, owing to a lack of strong utility and teamwide support, and her dependence on the right teammates or Ruler-heavy content keep her out of top-tier placement. Masters looking for either a solid general-purpose single-target Buster damage dealer or a defensively self-sufficient DPS will find that XX (Alter) can do a decent job for a while, until they can transition to stronger alternatives.

Good Single Target Damage Output

With a triple Buster card deck, an anti-Ruler bonus, a special attack modifier against [Lawful] and [Good] enemies (which are quite common for Ruler enemies), and her own Critical steroids, Mysterious Heroine XX (Alter) can put out serious single-target damage during her burst rotation. She especially benefits when supported by Critical Support Servants like Koyanskaya of Light or Van Gogh.

Good NP Gain for a Buster Servant

Between her third skill, which grants a substantial NP charge that scales higher with more enemies on the field, and the 20% NP refund from her Noble Phantasm, XX Alter boasts surprisingly good NP management for a Buster-centric Servant. Her rotation becomes even smoother when supplied with cooldown reduction and external NP battery support.

High Cooldown On Skills

XX Alter’s skills have relatively long cooldowns (7/6/7 turns at max level) due to the variety of effects they pack. This creates a noticeable drawback in drawn-out battles, as she relies heavily on active skill uptime to sustain her momentum. Since her NP charge skill is also on a 7-turn cooldown, it makes it difficult for her to do the Koya-Oberon 3-turn Buster Loop without having her Append 5 Skill leveled.

Lack of Strong Utility and Team Support

Beyond a long-cooldown AoE NP Drain, and any Critical Stars she generates, XX Alter offers virtually no team utility. She functions as a selfish damage dealer who requires the team to cater to her, unlike many modern damage dealers who pack both strong self-buffs and supportive team utility.

XX Alter has a clear skill leveling hierarchy, with her third skill taking top priority to get her Noble Phantasm ready as quickly as possible. Because her skills have long base cooldowns, any Master planning to use her regularly should aim to level all three skills to at least Level 6 for the cooldown reduction.

• Quantum Armor B – This skill functions as a self-buff, a Critical Star generator, and a survival tool. While the Attack buff and Star generation do scale with level, the numbers aren't particularly impressive, making it safe to leave for last.

• Gravity Manipulation B – This skill takes priority over her first skill because both its Buster performance and Critical Strength scale with level. Together, these buffs form the backbone of her overall damage output.

• Villains Terminate A – Since her NP charge scales with skill level and fast Noble Phantasm access is crucial for a burst-oriented Servant, this is easily her best skill and should be leveled first.

As a Buster Crit-focused single-target dealer that heavily depends on her Noble Phantasm for the bulk of her damage, Mysterious Heroine XX (Alter) wants Craft Essences that combine Starting NP Gauge with other offensive stats like Buster Card Effectiveness, Critical Damage, Attack, or NP Damage.

• First Day of Filming / Aerial Drive / Golden Sumo: Boulder Tournament: These offer flexible, easily obtainable combinations of Starting NP Gauge and offensive stats that suit her burst-oriented kit well in any general-purpose lineup.

• The Black Grail / Inverted Rain of Mud / Heaven’s Feel: Best for raw damage output, especially when paired with Oberon.