If you don't have Mauxir - Meow yet but want to try her out, she is available as a Trial Operative in Story Chapter 8 - "The Raging Wind".
Mauxir can create a target to shoot that deals damage to the host, allowing her to easily shoot even highly mobile foes whilst dealing good damage.
Role: Main DPS and ballistic or skill support
Frost Damage
Deals ballistic damage
Mobility is good
As a DPS
Spam her standard skill and shoot the target it creates
As a support:
Spam her ultimate skill as often as you can
If her support skill isn't active, then use it
Weapon:
DPS: Alloy Truth / Hypochlorous Acid
Weapon Parts: Max ATK
Support: Alloy Truth / Frigatebird
Logistics Squad:
DPS: Amano-Iwato
ATK, Alignment Index/Crit Dmg, Chaos Dmg
Support: Amarna
Max HP, Alignment Index, Chaos Dmg
Best squadmates for Mauxir:
Fritia - Little Sunshine
Standard Skill
Mauxir creates a target Avatar from the target enemy. Damaging the Avatar damages the host enemy. [The Avatar is not an auxiliary unit.]
The host takes 110% of the damage dealt to the Avatar.
Shots hitting the Avatar only give half of their U-Energy.
With its second Neuronic, defeating the enemy will reset the cooldown of the skill.
Since the host takes extra damage if the Avatar is targeted, you should always target the Avatar.
Support Skill
Just like her standard skill, Mauxir creates an Avatar from the target host enemy, and damaging the Avatar damages the host.
The Avatar from her support skill:
Lasts 8s instead of the 16s from her standard skill
Has only half the current HP of the host, rather than equal to its current HP
Only transfers 60% of the damage, not 110%
Can't be hit by shots (so skill damage only)
If you have some AoE damage, then you can use Meow's support skill to create an extra target for it to hit.
With its first Neuronic, it can be used to create targets from multiple enemies, allowing you to deal much more AoE damage.
With its second Neuronic, Meow automatically uses her support skill whenever any operative inflicts a control effect on the target.
This does not start a cooldown on her support skill, and you can use them after one another for high uptime.
When used with operatives that frequently inflict control effects (e.g. Lyfe - Wild Hunt) this can allow Meow very high uptime on her support skill.
Since it can't be hit by shots, and it transfers less than 100% of its damage to the host, you shouldn't aim at Meow's Avatar.
Instead, use AoE effects to hit both the Avatar and the host, allowing you to deal more damage.
Ultimate Skill
If the targets HP is lower than 150% of Meow's current HP, the enemy takes damage equal to its current HP, effectively instakilling it.
If the targets HP is higher than Meow's, then Meow's shots gain Frost aptitude - extra Frost damage per shot.
The extra damage can trigger up to every 0.5s, per target.
The extra damage is based on Meow's HP rather than her ATK. As such, +15% per shot is a lot of extra damage.
With her second Neuronic, other operatives gain the Frost aptitude effect.
With its first Neuronic buff, killing a target with her Ult refunds Meow with 90% of the U-Energy used and resets the cooldown of her ult.
Alloy Truth
Alloy Truth deals Chaos damage instead of the Frost damage of Meow
It does give a nice Max HP buff, as well as an ATK and Crit Dmg Amplifier buff on support skill use, and is thus generally Meow's best weapon if she is used as a support.
The ATK buff from Alloy Truth is based on Meow's HP rather than her ATK.
Hypochlorous Acid
This 4* weapon gives extra HP based on ATK.
Meow doesn't have high ATK (as she primarily wants HP, and hence doesn't get as much ATK) but it's still a good bonus.
Frigatebird
Mauxir is a decent support operative, meaning that the usual support SMG works well.
Frigatebird gives an ATK buff (based on Mauxir's ATK) for 15s after using her support skill.
Mauxir tends to want HP instead of ATK, but Frigatebird is still a great weapon for her if she is used as a support and doesn't have Alloy Truth.
For weapon Parts go with max HP, as Meow wants Max HP.
As a DPS, you can use:
Amano-Iwato
Amano-Iwato gives ADS ballistic damage.
If you don't want to shoot ADS, then Mizuho gives ballistic damage when shooting continuously.
Eli gives ATK, and gives +Frost damage after shooting non-crits.
The damage transferred by Meow's standard skill doesn't count as a weakspot and thus doesn't automatically crit, so Eli works well for her if (and only if) you're shooting at the Avatar created by her standard skill.
Eli doesn't work as well if you aren't shooting her standard skills target, as other shots can crit, which lose Eli's buff.
Meow's crits deal more damage than shooting the target from her standard skill, so if the target has a weakspot you're better off just shooting that.
As a support operative, you can use
Amarna
Amarna gives Max HP, and a ballistic damage buff for 15s after using a support skill.
Since regular shots can't be shot, a ballistic damage buff isn't ideal if using Meow as a support.
Meow's ult does give extra per-shot damage though, so Meow is still a decent ballistic support.
For stats:
If used as a dps operative, Meow wants max ATK and Max HP
Max ATK to increase her ballistic damage.
Max HP increases the damage from the per-shot damage of her ult
If Meow isn't shooting at the target from her standard skill, then Crit Dmg Amplifier is best, as she can just shoot the enemies weakspots for more damage.
Both Max HP and Crit Dmg Amplifier are good stats for Meow if using her as a main dps, but neither are as good as ATK.
If used as a support operative, Meow wants Max HP and Alignment Index.
Alignment Index gives max HP.
A max-roll of 106 Alignment Index gives 4.24% Max HP. Not as good as an actual Max HP roll, but still decent
If you don't have Mauxir at M1 yet then Skill Haste is a decent cope stat, as that gives higher uptime on her standard skill.
You usually only need 1 Skill Haste roll, as her standard skill has a 16s duration on a 20s cooldown.
Once Meo gets her first Manifestation, Skill Haste becomes useless if using Mauxir as a DPS, but can still be useful if using her as a support.
U-Energy Recovery is also a decent cope stat.
M1 increases the duration of all of Mauxir's avatars (i.e. targets/dummies) by 25%.
This increases the duration of her standard skill from 16s to 20s - the same as its cooldown.
This increases the duration of her support skill from 8s to 10s - still lower than its cooldown, but better.
Combined with its Neuronic, M1 Meow can still have good uptime on her support skill.
M2 causes enemies with an avatar who are at less than 20% of Mauxir's max HP to take damage equal to their current HP (i.e. instakilling them).
Combined with its first Neuronic that automatically recharges the skill if it kills an enemy, M2 can allow Mauxir to just spam her standard skill to clear groups of trash mobs.
This is not a particularly efficient way of clearing groups of mobs, but it can work.
If an enemy is so weak that it has less than 20% of Mauxir's max HP, then you can probably kill them by just shooting a few times instead.
M2 basically removes 20% of Mauxir's Max HP from the enemies HP, which isn't much.
M3 causes the Avatar to lose 1% DEF for every 1% of HP it loses.
This means that the Avatar (and thus its associated host) takes more damage the more HP it has lost.
This is potentially a very high amount of DEF reduction, and thus does average a lot of extra damage.
M4 increases the level of Mauxir's support skill by 1, and increases the damage transferred by around an extra 10%.
Since this still doesn't increase it to over 100%, you're still better off shooting the enemy anyway.
M5 causes all nearby Avatars to explode when one Avatar or its host dies.
The damage is pretty good, but only against groups.
M5 does make Mauxir much better against groups, but she's still not a good choice for clearing groups.
As a 4* operative, you'll get all of Mauxir's Manifestations eventually anyway, but none of them really fundamentally change how she is played or why you want her on your team.
If used as a main DPS, Mauxir deals ballistic damage, meaning that the best operative to buff her is Fritia - Little Sunshine, who adds extra [Thermal] damage per shot.
If used as a support operative, Meow's Support Skill adds a target that is useful for dps operatives who deal AoE skill damage.
Meow's ultimate skill adds per-shot Frost damage, meaning she is works well to support operatives that deal a lot of hits with ballistic weapons (e.g. Wednesday, Lionheart, Little Sunshine, etc.)
That her support skill creates a target that can't be shot, but her ultimate buffs your operatives shots does combine to mean that Mauxir doesn't work perfect with most operatives, and no 4* operative.