Arclight Guide and Best Build

Kit Intro

Arclight is a 5-star, Electric, Sword Vanguard, sporting one of the lowest Combo Skill cooldowns in the game and able to be constantly attacking, all the while providing decent Electric DMG bonuses for her team.

Although Arclight has limited ways to build Electric Infliction and Electrification (only through her Ultimate), whenever Electrification is applied, her Combo Skill triggers. Her Battle Skill can then consume the Electrification and trigger it again, refunding some of the SP spent in the process.

This results in a loop of applying and consuming the reaction, weaving in Combo and Battle Skills between ally attacks. After enough uses of her Battle Skill, she buffs all Operators for a short period, so aligning this with a team's burst is critical to getting the most out of her.

Despite being a Vanguard, Arclight isn't a particularly good SP battery. Even with her P1 - which increases the SP recovery on her Battle Skill - she is a net drain of a team's resources.

On the other hand, the fact that she recovers - not returns - SP when her Battle Skill consumes Electrification is a significant value add. Many of the teams she runs in can struggle to build enough Ultimate Energy to align with their rotations, requiring a high number of team Battle Skill casts to sustain them.

Many other Vanguards have their SP recovery tied to Ultimates, making them more inflexible in openers as they haven't had the time to build enough Ultimate Energy themselves.

Arclight then fits the battery niche perfectly, being a character that demands frequent Battle Skill uses for her buff and refunds much of the SP spent for it, leading to consistent team-wide Ultimate Energy generation throughout a fight.

Combo

"Peal of Thunder" is Arclight's Combo Skill, and it sees very frequent use. It's triggered whenever Electrification is applied or consumed, and she will unleash a flurry of Physical DMG slashes while recovering some SP (10 at M1 and above).

This skill is unique in many ways. It boasts some of the lowest Combo Skill cooldowns in the game, at 3 seconds (M3 does not reduce this), making weapon and set effects that demand SP recovery easy to maintain. It also differs in its properties: unlike other Combo Skills it does not generate 10 Ultimate Energy for Arclight, but only 5 per cast instead. As she can get 2 uses of it per Electrification it adds up to being the same, but this often demands Battle Skill usage.

Its timestop is also absolute. Where other Combo Skill timestops have no effect on Operators' cooldowns, Arclight's does, meaning that it cannot be used to "shorten" cooldowns relative to buffs/debuffs.

Battle Skill

"Tempestuous Arc" is Arclight's Battle Skill, being the key to her high team-wide Ultimate Energy generation. By itself, it's unremarkable, dealing negligible amounts of Physical DMG and nothing else.

If, however, the enemy has Electrification, then it will consume it and deal an additional attack that has its own stagger build, deals Electric DMG and recovers SP (up to 40 at M3). This has the added benefit of triggering Peal of Thunder, which then recovers even more SP.

This skill's recovery is further enhanced by Arclight's P1, giving it another 10 SP in recovery when triggering the additional attack.

Despite its SP recovery, even with it at P1 and with 2 Combo Skills - one from the Electrification being applied and another from it being consumed - Arclight remains a net drain on SP, generating up to 70 SP but using 100.

Even then, it's still worth using, as it has an effective cost of 40 to 30 SP (depending on Potentials), while still generating the same 6.5 Ultimate Energy that a 100 SP cost Battle Skill does. It's with proper use of this skill that Arclight can function as an Ultimate Energy battery, and is needed to activate one of her Talents.

Talents

"Wildland Trekker" makes it so that when her Battle Skill's additional effect is triggered 3 times, it buffs the entire team's Electric DMG by 0.08% per point of Arclight's Intellect, lasting 15 seconds. This is further enhanced by her P3, being boosted by x1.3, and her P5, requiring only 2 triggers for its effect. 

As Arclight is likely to run Frontiers, which has many Secondary Attribute boosting pieces, she can reach well over 450 in Intellect without any artificing, having anywhere between 35% to well over 50% in Electric DMG bonus depending on investment level.

Despite the high number, it's difficult to make proper use of this buff without Potentials, as it demands multiple Electrifications to be consumed. With 3 casts of her Battle Skill, she needs her Ultimate to sustain reactions without sacrificing team damage, as Electrification should ideally be up for burst periods (not to mention the steep SP cost). 

Just aligning Ultimates though is itself demanding of her P4 and/or sacrificing team-buffing sets, as sustaining the Ultimate Energy for it isn't easy (e.g. using Redeemer's over Frontiers). 

It is a strong buff however, and is much easier to manage as Arclight's Potentials increase.

"Hannabit Wisdom" is Arclight's second talent and is rather unremarkable. It gives her a 50% chance to ignore Arts Inflictions applied to her, being a minor defensive boost that can help with survivability against certain enemies.

Ultimate

"Exploding Blitz" is Arclight's Ultimate, costing 90 Ultimate Energy (76.5 at P4) and is the only way that she has to apply Inflictions and Reactions.

It's a 2-part skill, where she will dash through and attack enemies, immediately applying 1 Electric Infliction. After a short while, lingering sparks along the path will detonate, where if the enemy has Electric Inflictions it will consume them to forcibly apply Electrification.

This is important to keep in mind, as if the Electric Infliction from the 1st part of the Ultimate triggers a reaction, there will be no second Electrification applied by the Ultimate, as there would be no active Electric Infliction on the enemy.

A key property of this ability is that the Electrification it applies scales with the number of Inflictions consumed. Consuming 4 stacks would lead to a 4-stack Electrification, despite it being forced.

This isn't as useful as one might think, as Arclight isn't built for Arts Intensity, so the damage increase effect is comparatively weak. In some Operators' cases, like Perlica, Potentials can further enhance the strength of their Electrification, making even a 1-stack forced Electrification from them stronger than a 4-stack from Arclight if properly built.

Still, as it applies both an Electric Infliction and Electrification, it's an SP-friendly way to sustain her own Combo and Battle Skill use, as well as other Operators' Combo Skill triggers and/or item and set effects - such as getting an Arts Burst between the Electric Infliction and forced Electrification from the Ultimate.

It also has a long area of effect, although it can be hard to aim, so swapping to Arclight for a brief period to position for it in situations where multiple enemies need to be hit is recommended.

Basic Attack

"Seek and Hunt" is Arclight's Basic Attack, and unfortunately, it's rather weak. Although she is an Electric Agent, this skill deals only Physical DMG, Finisher included.

The 4th hit of its sequence - a long sword boomerang throw - can be animation cancelled as soon as it deals a tick of damage to enemies. This means that in practice, Arclight's Basic Attack string can be looped surprisingly fast.

One might think that if the priority then is SP generation and stagger build, it could have some use, but as she is frequently casting her Combo and Battle Skill, these interruptions mean that in practice it ends up being far slower than that of others in her team.

Gameplay

Arclight’s gameplay is all about cycling through her skills: use her Combo Skill when Electrification is applied, then use her Battle Skill to consume it for another Combo Skill use, eventually building up to her Wildland Trekker talent buffs.

Ideally, the Battle Skill should be used as late as possible, so that currently active Operators can benefit from the Arts DMG taken buff that Electrification provides, but unless other Operators' Combo and Battle Skills are being used in this period, it isn't all that significant.

As her Ultimate provides Electric Inflictions and Electrification separately, it can be useful to time it around Final Strikes or before staggers to set-up for buffs, being a perfect opportunity use Arclight's Battle Skill for Wildland Trekker activation right before a burst period, especially as other characters are likely to supply more potent Electrifications than Arclight owing to the difference in Arts Intensity. 

The delay between the Electric Infliction and forced Electrification is useful too, as it can be used to set-up Arts Bursts by other Operators to trigger weapon and set effects.

The skill barrier to Arclight is understanding when and when not to use her Battle Skill. If it's consuming an Electrification right before a burst, it may trigger Wildland Trekker, but mean that the team loses out on the much more valuable Arts DMG taken multiplier from the reaction.

To sustain Wildland Trekker without P5, she needs 3 uses of her Battle Skill, and this is important to track. It'd demand 4 total Electrifications to be inflicted on enemies - 3 for Arclight to consume and 1 that remains on the enemy for the burst. With the high amount of stagger that she builds, doing so is unfeasible without her Ultimate, which is unlikely to align without her P4 and/or Ultimate Gain Efficiency pieces.

On the flipside, with only 2 Battle Skill casts needed (at P5), one may need to delay Arclight's Battle Skill or, again, rely on her Ultimate for Electrification, as otherwise Wildland Trekker may fall off by the time an enemy staggers or burst is due to land.

This means that to get the most value out of Arclight, one needs to adapt rotations to her current investment level, with SP, Ultimate Energy and reaction alignment all factoring into her gameplan.