Mauxir - Shadow Ka

Mauxir - Shadow Ka is not currently available as a Trial Operative in any story mission, so if you don't have her the only way to try her is to wait for her banner so she has a trial.

Mauxir's support skill provides a stationary target that you can damage, which causes the enemy the skill was cast on to take extra damage, with Mauxir also providing several ballistic damage buffs as well.
This makes Mauxir a pretty general damage support, but she is best used as a support for ballistic-damage operatives, ideally those with slower-firing weapons.

Powercreep has meant that Mauxir isn't nearly as useful as she used to be, but she's still a capable support.

The Basics

Role: General Support
(mostly buffs ballistic shots)
Deals Chaos Damage
Weapon Type: SMG
Deals mostly ballistic damage
Mobility is not great

How to use Mauxir - Shadow Ka

As a support:

Spam her support skill off-cooldown
Aim at the target created by Mauxir's Support Skill

How to build Mauxir - Shadow Ka

Weapon: Alloy Truth / Wave
Weapon Parts: Max ATK
Logistics Squad: Amarna (Twilight also good)
+10.0% Max HP
+19.3 Skill Haste
+8.5% Chaos Damage
Best teammates:
Mauxir works with all dps operatives
Ideally any operative dealing ballistic damage
Ideally with a shotgun or sniper.

Specifics:

Standard Skill

Mauxir's Standard Skill causes her to start Kebachet (i.e. "a bomb") towards the target.
You can hold her standard skill to charge it up, increasing in level up to twice, which results in more damage, a larger AoE, being thrown further, and it also pulls enemies in too.
This uses 5 Stamina every 0.3s, which is a lot.

This counts as Auxiliary damage, and hence is affected by Aux unit buffs, and it uses its own stats (which are inherited from Mauxir, but it doesn't inherit her buffs).

The damage of this skill is entirely determined by Mauxir's Max HP stat, not her ATK.

Ultimate Skill

Mauxir deals damage in front of her, and Slowing the target for 2s (or 5s with its Neuronic buff, which also adds a strong DoT).
This also creates an AoE that deals much higher damage after a short delay.

The damage of this skill is entirely determined by Mauxir's Max HP stat, not her ATK.

Support Skill

Mauxir has Kebachet bind the target (and up to 3 sub-targets, or 5 with her Neuronic), dealing Chaos DoT damage every second.

You can deal damage to Kebachet, which deals damage to the target being bound.
Since Kebachet transfers 110% of the damage it takes, damaging Kebachet results in more damage than damaging the enemy directly.
Kebachet is not a weakspot though.

Mauxir can't swap in whilst this skill is active - you have to wait for it to expire or use her support skill again to end the skill early in order for her be able to swap in.

Mauxir can't bind invulnerable targets.

This skill lasts 10s, and it goes on its 26s cooldown after that 10s duration ends, so its uptime is very low (27.7%).
This skill also uses 30 S-Energy, which is a very high cost, but its very long cooldown means that Mauxir doesn't actually run into any S-Energy issues.

The damage of this skill is entirely determined by Mauxir's Max HP stat, not her ATK.
2% Chaos Damage per second sounds terrible, but that's 2% of Mauxir's Max HP, which is much stronger.
The DoT damage isn't the reason you use this skill though - it's for the 110% damage transfer, allowing you to deal more damage to the enemy.

Weapon

Alloy Truth
Her 5* weapon, and her best weapon.
Gives her a nice Max HP buff, but after using her support skill gives an ATK buff based on Mauxir's Max HP, as well as a Crit Dmg Amplifier buff, albeit not with 100% uptime.
Alloy Truth is Mauxir's best weapon, but the Crit Dmg Amplifier means Mauxir performs better when supporting ballistic operatives, as skills can't crit.
Wave
Her 4* weapon.
Gives a stacking ATK buff after Mauxir's support skill deals damage, based on Mauxir's Loadout Max HP.
Being based on her Max HP makes Wave a strong buff.
Frigatebird
Gives the deployed operative an ATK buff after Mauxir uses her support skill.
The ATK buff is based on Mauxir's ATK stat, so it's not that strong as Mauxir really doesn't want to buff her ATK, only her Max HP.
if you don't have Wave though, Frigatebird is her best support weapon.

For Weapon Parts, Mauxir wants Max HP, as all of her damage and effects scale off her Max HP.

Logistics

Amarna squad is Mauxir's designated and best logistics squad.

Amarna gives a 15s +30% ballistic damage buff, and +20% ATK for 1.5s after their support skill deals damage.
Since Mauxir's support skill deals damage every second, Mauxir can maintain the +20% ATK buff as long as her support skill is active.

For stats
For the Special talent, Mauxir wants +8.5% Chaos Damage
For the basic stats, Mauxir wants:
+10.0% Max HP
+19.3 Skill Haste or +106 Alignment Index

If using Frigatebird, then Mauxir wants ATK instead of Max HP, but since Mauxir's ideal endgame weapon is Alloy Truth and Wave is a great 4* weapon for her - both of which want Max HP and not ATK, you're better off going for Max HP to begin with, rather than going for ATK and then having to re-roll your logistics to Max HP later.

Alignment Index
The deployed operative gains 1 stack of "Diacletics" every second. When at 10 stacks, the next shot they fire has +100% Crit Rate and gains +80% Crit DMG Amplifier.
Each 100 Alignment Index gives an extra 20%.
Operatives that have higher-damage but low-RoF weapons will benefit more from this.
Operatives with weapons that have a high-RoF and low damage-per-shot will benefit less.

Boosting the damage of a single shot is nice, but only proc'ing once every 10s means it isn't a large dps increase for most operatives.

You're generally better off going with Skill Haste in order to allow Mauxir to use her Support Skill more often, but for very short fights Alignment Index can be great.

You can also use Twilight squad, which gives a -16% Resistance decrease for 5s after being damage by an active skill.
Since Mauxir constantly deals Chaos-damage, Twilight squad will reduce the enemies Chaos Resistance.
Since Mauxir's support skill continuously deals damage, she can maintain this for the entire duration of her support skill.

Twilight allows Mauxir to perform much better when supporting non-ballistic (i.e. skill-dmg) operatives, but only if they deal Chaos damage.
There aren't many Chaos-damage skill-damage operatives you'd want to use Mauxir with though, so using Amarna to support ballistic-damage operatives is still the best way of using Mauxir.

Manifestation

M1 gives shots that hit the Kebachet deployed by her support skill extra Crit Rate.
+100% for snipers and shotguns, +50% to pistols, and +25% for AR's and SMGs.
In most circumstances, this is a large damage bonus when shooting at the target.
Since you could potentially be shooting a weakspot instead of her target, M1 mostly just makes up for the shortfall of her target not being a weakspot in the first place.
M2 decreases the ATK of the targets bound by her support skill by 20%.
Whilst this might be a nice survivability bonus, it doesn't increase your damage in any way.
With M3 and a Chaos-damage weapon, the duration of Mauxir's support skill is increased by 0.1s per 1,500 Max HP.
Given that Mauxir has a lot of Max HP, this is a decent duration increase - Getting Mauxir to over 60k HP is not that hard, which translates to +4s duration.
The uptime is still low though.
M4 gives the usual +1 level to her support skill, decreasing its cooldown to 25s (from 26s)
A lower cooldown is nice, but the uptime is still low.
M5 increases the amount of damage her standard skill transfers from 110% to 120%.
This is really strong.

For max damage you'll want M5.
M1 is a very good damage increase and requires little investment.
M3 gives a good buff, but needing to take the mostly-useless M2 means the investment needed for it is quite high.

Good Teammates for Mauxir - Meow

Mauxir can be used as a generic support for all operatives, allowing them to deal damage to Kebachet from Mauxir's Support Skill to deal extra damage to an enemy.

Note that Mauxir's Support Skill deals continuous Chaos-damage, so if you're using both Mauxir and Vidya - Celestial Swan, you will want the main dps to also deal Chaos damage.

Mauxir works best as a ballistic damage support, buffing ballistic operatives via her M1, weapon effect, and logistics set.
As such, Mauxir works best with ballistic operatives, ideally ones with a high damage-per-shot and low-RoF to gain the most benefit from her Deiwos passive.
Ideally operatives that use a shotgun or sniper, to maximize her M1, but pistols gain a lot of benefit too:

Yao - Winter Solstice
Bubu - The Geomancer (Note that Bubu has 100% crit chance for her ult anyway, so she gains less benefit from the added crit rate from Mauxir's M1.)
Mia - Starchaser (Note that Mia has 100% crit chance anyway, so she only benefits from the Crit Dmg Amplifier and damage transfer, not the extra crit rate)
Fenny - Coronet (Note that Fenny has a naturally very high crit chance anyway, so she doesn't gain much from the extra crit rate from Mauxir's M1)

Basically any operative that deals a lot of damage with slow-firing shots.

Mauxir does also work with ballistic operatives with higher fire rates, but the effect of her Deiwos passive will be reduced.
If you don't much care about her Deiwos, then you'll want to use Mauxir with operatives that deal ballistic damage, ideally from a sniper or shotgun, or maybe pistol, to maximize the effect from Mauxir's M1 buff, however Mauxir still works well for all ballistic-damage operatives.

Mauxir can also be used to provide a stationary target, which is useful for operatives that have trouble hitting highly-mobile enemies:

Fenny - Coronet
Coronet has a short range, so highly mobile enemies can be a problem for her - A problem that Mauxir can solve.
Haru - Raikou
Raikou is a skill-dmg operative, but the stationary target can be really useful to her.
Raikou also deals Chaos-damage herself, allowing Raikou+Mauxir to be used with Vidya - Celestial Swan.
Cherno - Enigma
Enigma is a skill-dmg operative, but the stationary target can be really useful to her to allow her voids to consistently stay on top of an enemy.
Enigma also deals Chaos-damage herself, allowing Enigma+Mauxir to be used with Vidya - Celestial Swan.
Nita - Pulse
Enigma is a skill-dmg operative, but the stationary target can be really useful to her.
Haru - Absconditus
Absconditus is a skill-dmg operative, but the stationary target can be really useful to her.

Skill-damage operatives won't benefit from Mauxir's Amarna logistics squad, or her crit buffs, but the stationary target can allow them to deal much higher damage by virtue of just being able to more consistently deal damage themselves by just hitting the stationary target from Mauxir's support skill.
Mauxir can still use the Twilight logistics squad to debuff enemies Chaos Resistance, which is useful for dps operatives that deal chaos damage themselves.
If they don't deal Chaos-Damage, then Mauxir won't be able to use a logistics set to provide skill-damage operatives much benefit at all, meaning Mauxir provides a stationary target that increase their damage a bit, some ATK buffs from Mauxir's weapon, and not much else.