Mash Kyrielight

Your very first Servant and most prominent partner in the story, Mash leaps into battle with shield at hand, ready to defend Chaldea from any danger. With a balanced, Arts-leaning deck, and a skill set which lends itself to defensive or stalling strategies, Mash can slot into just about any team due to her universally useful defensive utility.

Although she starts the game as a 3★ Servant, with Ascension and some skills locked for story reasons, once her powers reach their height she becomes a well-rounded utility tank. Mash can use her good bulk, defense-oriented skills, and her lack of any class weakness to shield frailer Servants in every situation- at the cost of having little to no offensive presence. Her unique party cost of 0 opens up countless options for team composition and higher-ranked Craft Essences that costlier defensive options would have to forego.

Mash Kyrielight Upgrade Conditions

Great Team Survivability

One of the biggest draws for using Mash is that unlike many other defensive Servants, both her first skill and her NP apply large defense buffs to the entire team. As if that weren’t enough, she also possesses one of the few targetable invulnerability skills in the game. Combined with her taunt, she can easily tank single-target Noble Phantasms and walk away without a scratch. Unfortunately, due to the nature of her buffs, Mash is very susceptible to enemies with the ability to ignore defense, so it’s important to keep an eye out for them.

Offensive Support

Despite being primarily a defensive character, Mash possesses two useful tools for assisting damage dealers; her upgraded NP gives her two allies a substantial attack buff, and her second skill can be used to feed any ally 20% NP charge in a pinch.

No Class Disadvantage

Mash is the only Servant in the entire game who takes neutral damage from every single enemy, making her the prime defensive option when facing Berserkers, as well as for fights with a variety of enemy classes. This forms a key part of her ability to fit into just about any team for any fight where she’s needed.

Strong NP Gain

With her double Arts deck and an Arts NP, Mash can easily form Arts chains with allies. When her taunt is up, however, Mash gains absurd amounts of NP charge; a maxed Shield of Rousing Resolution will give Mash a ridiculous 500% NP generation when attacking for one turn.

No Class Advantage

Despite the defensive perk of being neutral to every class, Mash conversely doesn’t gain defensive bonuses against anyone, meaning for single-class nodes she may not be ideal. Though her attack stat is fairly average, without class advantage  her cards will deal below-average damage. Essentially, she is relegated to being a defense and support unit with very little in the way of direct offense, while her cards are usually only chosen to fill out chains or grant first-card bonus unless her taunt is active.

Story-locked Progression

The discussion of Mash’s strong skill set and NP is mostly geared towards the long run; unfortunately, Mash begins the game without her useful third skill or any upgrades to her other skills, and even her ascensions are gated by completing story content. It’s worth noting that even with her pre-buffed kit, her 0 party cost still makes her an effective choice for teams in the early game when costs are more constrained for low-level masters.

• Transient Wall of Snowflakes

  Maxing this skill second will contribute greatly to the overall resilience of the party due to its three turn uptime and short five turn cooldown. Although the upgraded version’s significant damage cut doesn't scale with levels, the lowered cooldown means it can be applied more often.

• Obscurant Wall of Chalk

  The utility of this skill is extremely powerful and it should be maxed first. Doing so drops the cooldown to a reasonable 7 turns and increases the NP charge to 20%, providing flexible help with both farming and difficult content.

• Shield of Rousing Resolution

  The main draw of the ability is the taunt, which lasts for one turn at all ranks. Though the NP gain increases significantly at each rank, it is more than sufficient to build up Mash’s NP at rank 1. The skill is still powerful and benefits from a reduced cooldown, but can safely be maxed last without greatly hurting Mash’s combat performance.

As the majority of Mash’s value in battle comes from her skills and her NP, a priority should be placed on Craft Essences that passively empower her or her allies, and don’t require you to use her comparatively lackluster basic cards. Therefore, Passive NP Gain, Passive Critical Star Generation, Starting NP Gauge, additional Defense Up, CEs that activate on Entry, Taunt CEs, or Event Craft Essences are optimal choices.

• Prisma Cosmos / Premonition of Beginnings: Prisma Cosmos is a fantastic option to give Mash passive NP generation and let her use her powerful NP without having to use her weak normal cards. 
• A Fragment of 2030 / His Rightful Place: For Masters who want to take a more offensive support approach, having Passive Critical Star Generation helps to improve both the main damage Servant's offense, but also helps to improve NP Gain of the entire team by allowing for more Critical (Arts) cards.
• Kaleidoscope / The Imaginary Element / Dragon's Meridian: Especially for faster-paced fights, it can be very useful to get Mash’s first NP up as soon as possible. By combining Starting NP Gauge CEs with supports or her Obscurant Wall of Chalk, Mash may be able to NP straight away.
• Holy Shroud of Magdalene Iron-Willed Training / Azoth Blade: Mash can stack her Defenses so high that normal enemies can hardly scratch her. As damage is first reduced by her Defense Up before applying the flat Damage Cuts in her kit, adding additional Defense Up CE can greatly improve her survivability at max skill levels. 
• Golden Captures the Carp / Holy Maiden's Teaching: Some enemies can be so destructive that using Mash as a short-lived Tank is her best use. In such cases, using CEs that grant a chunk of Critical Stars is great for trying to keep the enemy boss's life equally short. 
• GUDAGUDA Poster Girl: Often enough, a single turn of Taunt is not enough to distract a dangerous (Berserker) enemy. Extending the Taunting period is a great way to buy more time.
• Event Drop CEs: Though they may not benefit her directly in-combat, Mash is commonly used to hold event-specific CEs due to her 0 cost to field. Fielding expensive 12 cost CEs can add up quickly, and Mash is a cheap way to reduce the AP/time spent farming by slotting more Event CEs than otherwise possible.