Yu Mei-ren (Lancer)

“I don’t feel like changing. I mean, Xiang Yu complimented this swimsuit.”

When Xiang Yu told Yu Meiren to get in a bathing suit and enjoy summer, her true nature emerged even if she’s a bit tsundere about it. As a Single Target Quick Lancer, not only did Yu transform from an Assassin to a Lancer, she transformed from one of the worst Servants in the game to one of the premiere male boss killers around.

Yu’s kit is packed to the gills with all one needs to kill a man. Her burst damage is insane thanks to Dance of Bygone Days EX’s ability to both boost her Quick and the party’s Critical damage. Combined with her Supereffective modifier on her Noble Phantasm against men, there’s no chance. With the right supports, she also has great sustained damage as well, having high crits for several turns. And of course, she has the right self-sufficiencies with a charge on Conqueror's Princess EX and a Guts on Summer Incarnated Elemental A+.

The main problem with Yu comes from her sustainability. While she does have a Guts skill to survive one time, that is counteracted by how she’ll receive all hits the turn she uses her Conqueror's Princess skill. She’ll also have a bit of problem with NP gain without support even with her boosts. It’ll also be a challenge getting stars to her as she has minimal generation.

Yu is used by Masters as a boss killer, capable of doing close to a million damage on her Noble Phantasm with the proper setup against Male Archers. The only real question is whether she really did change her clothes because Xiang Yu told her to, or if she just was tired of being a bottom of the barrel Assassin.

Burst Damage

Yu has so much going for her with Burst Damage that she competes with even some top tier boss killers like Scathach for one-hit strength. Her Noble Phantasm alone is Quick type which makes it slightly more powerful than others, but comes with a 50% bonus against Males. As this is tied to her Noble Phantasm, it applies multiplicatively with Craft Essence boosts such as NP Damage up or event damage bonuses. If that weren’t enough, she gets a huge chunk of damage boost from her Quick crits, dealing an extra 50% for every Crit. A NPQQ chain in theory could deal close to 1.5 million damage with a Black Grail and a double Skadi support.

Sustained Damage

Yu’s biggest buffs to her Crit and Quick last 3-turns on a 5-turn cooldown, so she will not be long without them in any extended fight. As these are sizeable boosts, she is able to deal damage throughout the fight if needed. 

Self-Sufficient

Although supports help her immensely, Yu has what all Servants need to operate independently. For the NP side of things she has a charge and NP gain rate buffs (which can increase on certain fields types). And for survival, she has a pretty heft guts reviving her with about half health.

Low Durability

Yu does have a Guts to survive, but this may in effect be cutting her health in half from the start. Her charge skill brings the attention of all enemies to her for a turn, and without an evasion or invincibility she’ll be taking that as damage. Seeing how she’s likely facing bosses, this could be enough to knock her main first HP bar out.

Low Natural NP Gain

Yu has a relatively high NP gain modifier at 1.1% per hit, but her card’s hit counts are rather low with only a 3-hit Quick and 4-hit Extra. While this is boosted some by Summer Incarnated Elemental, she’ll likely have to rely on supports for the rest of her gauge. 

Low Star Gain

As a Single-target Lancer, Yu has difficulty producing her own stars unlike some of the other Quick Lancers. Her lower hit counts make it hard to produce a stash of stars, and her supports likely will not be providing much either for her without CEs.

A master going into a boss fight with Yu would want to use Dance of Bygone Days EX as soon as possible to take advantage of her Crit damage. This skill could debatably be leveled first, but should always go to max. Conqueror's Princess is a nice way to access her Noble Phantasm earlier, but is dangerous to use unless Yu is protected somehow. Summer Incarnated Elemental is without a doubt the weakest of her skills only offering trivial levels of NP gain rate and HP.

• Summer Incarnated Elemental A+ is Yu’s main survival tool, offering a 1-time guts which lasts for 5 turns. With a 6-turn cooldown at max level, this skill could in theory allow her to almost always have a guts on. For this reason alone it is suggested to level this to max, but at last priority. The skill also offers her 20% bonus NP gain rate and another 20% if she’s near water or sunlight, but these wind up being far too situational to target. 
• Conqueror's Princess EX is Yu’s battery, providing up to a 20% charge to any party member. Typically Masters are going to use this on Yu herself to top her off, but it could in theory go to a support for situational reasons. While it has a low cooldown of five turns, it does attract all attacks to Yu for a turn without Yu having any way to defend herself. If one is available, this in tandem with Summer Incarnated Elemental could give her a massive boost in NP gauge thanks to hits taken from enemies. Level this to max and at top priority if you favor her NP, or second if you favor her Critical capacity. 
• Dance of Bygone Days EX might as well be cheating. For 3 turns, she will not only get a small boost to her Quick cards, but a major Crit damage boon which applies not only to herself but the entire party. On a mere 5-turn cooldown, she can have this active almost constantly, dishing out criticals as needed. If you favor Critical capacity, level this first, or second if you prefer her NP, but always to max.

Yu’s kit is primarily centered around Noble Phantasm damage, so her CE should primarily focus on boosting that skill up. She benefits from the standard suggestions of NP Damage Up CEs if one can charge up her gauge with supports, Starting NP Gauge CEs if one cannot or wants to use her for multiple NPs with supports, or Mixed Damage / Starting NP Gauge CEs to get a little bit of both worlds. With her NP gain and the right cards, a Mixed Starting NP Gauge / NP Gain Rate CE can sometimes substitute for the better Starting NP gauge CEs for the same effect. Lacking a NP Damage up, a Burn Supereffective CE could have some lesser benefits.

• The Black Grail: If facing an enemy with a large HP bar, this would be Yu’s goto CE, using it to boost her power up and multiplying with her NP damage supereffective modifier against males. 80% NP Damage boost is still an 80% NP damage boost. Masters should be careful about using this without Summer Incarnated Elemental maxed as its health tick could kill her in longer fights.
• Kaleidoscope / The Imaginary Element / Dragon’s Meridian: Standard starting NP gauge CEs help Yu unleash her Noble Phantasm earlier in the fight.
• Knights of Marines / Holy Night Supper / Golden Sumo: Boulder Tournament: Usually, a Servant with so many Quick boosts does not get Knight of the Marines suggested first, but with her 20% self charge, she only needs another 20% (possibly acquired via coins at bond level 12, a support, or a Mystic Code) to use her Noble Phantasm. Without that 20%, the Knight of the Marines’s 60% is trivial, so the other suggestions will boost up her damage further with a 50% start.
• Magical Girl of Sapphire: In a double Skadi setup, Yu with a MLB Magical Girl of Sapphire will regenerate 20% or more of her gauge so long as she’s able to do 1 overgauge hit, get 1 non-Buster attack in after her Noble Phantasm, or have a Mystic Code Quick support from Chaldea Pathfinder or Tropical Summer. This combined with a 10% charge from those Mystic codes, her own 20% charge, and a second Skadi’s 50% gauge boost would allow her to use two consecutive Noble Phantasms, similar to a MLB Kaleidoscope. 
• Honey Lake: Yu’s Noble Phantasm inflicts a 3-turn Curse and Burn debuff to its victims. Honey Lake can take advantage of this with its 40% Powermod against victims of Burn. It admittedly is not as powerful as it should be in theory as it stacks additively with her Critical damage, and the burn effect comes after damage in the Noble Phantasm, but if a Master can get off a second Noble Phantasm within 3 turns, this could serve as a good midway point between a mixed CE’s damage and a Black Grail’s damage boost.