Azura

Inspired by Gins from Facebook groups. Azura is fast enough for a firesweep build to safely poke for damage. WoM can be replaced with any chill ability or wrath to either support units or get in extra damage respectively. Drive skills are recommended for the C slot to support units after teleporting in from WoM. Speed +3 to make firesweep more potent, this can also be drive defense for more team support.

For the love of god, protect her from any stiff breezes.

[Final Build]
Sapphire Lance+
Sing
Moonbow
A: Armored Blow 3
B: Wings of Mercy 3
C: Fortify Res 3
S: Hone Atk +3

Merged +4
Sacred Seal: Hone Spd 3

Immortal to most reds especially when buffed with spurs. Buffs both Speed and Attack to adjacent allies and is an excellent singer.

I got a minus speed and plus attack Azura recently from the bound of heroes banner that was release. As this build is a focus on countering reds through the use of Sword breaker and Sapphire Lance +. As I decided to use both Darting blow and a +3 Speed Seal to make up for the -speed bane (Allowing her to own 39 Spd when she initiate). As the use of Threaten Speed 3 on her C skill which help her with being able to double most fast Sword users that own a speed 39. In case of any sword users that own a speed faster than 39, sword breaker will make sure that she is able to double swords users regardless. Moving on to the skills and super ability, you should keep Azura as a singer even with an offensive build such as this one, as she is meant to only attack when she needed to do so. Such as a situation where your bow or sword user can't kill another sword or red, as you would use her to tank a sword as well a red mage too because of her decent default res to get the enemy low or finishing them off entirely. Which she would be later switch back to the backline and be used as a dancer/singer again for your team. As for her super ability, I used Moonbow as it has a low cool down and will help her potentially oneshot armor reds.

*Note: This Azura, Lady of the Lake build is a theory craft tailored to go along with my Lyn, Lady of the Plains [Brisk Winds of Sacae] build. My Lyn and Azura are S-rank supporting allies.

As opposed to the statistical breakdown and analysis provided for Lyn's build, this will more or less explain the reasoning behind the skill choices and team comp. This will still be rather long however, so you can move on, if you don't feel like reading a wall of text.

My name for this Build is [Aria: Serene Swell of a Midwinter Lake]

My ideal ivs for her is +Spd -Def and at +10 merge, with a Res forged Berkut's Lance (Gives +5 HP and +4 Res), and Wind Blessing (Gives +3 HP and +4 Res) her stats are: 48 HP/49 Atk/40 Spd/22 Def/40 Res.

Some of you may be asking, why not a speed forged weapon since she's got a speed boon (or giving her a Water Blessing)? My first reason is to make up for her lower BST since she is a dancer/singer. She receives 1 extra BST from resistance forges/blessings (+4) as opposed to (+3) from speed forges/blessings, since I care about min-maxing (I won't be using her in my first team for Arena Assault unfortunately).

My second reason is that I needed a proper res tank (and preferably one that was capable of counter-killing) red mages; but I didn't want to give up Azura at the same time because of her utility. Thankfully, a weapon refined Berkut's Lance can make most Lance heroes pretty good at tanking magic hits by giving them an additional 7 res if initiated upon (Azura can reach up to 47 Res on her own); not to mention that she handle a bunch of green mages just fine.

And lastly, a vast majority of top tier speed units sporting speed boons, speed forged weapons, and Water Blessings, will seldom surpass the 50s in terms of speed; the only way I've seen this happen is if the Hero stacks blessing bonuses, utilizes a Speed +3 Sacred Seal in addition to permanent stat changing A skills such as Fury and Life & Death, and/or receives the appropriate buffs.

As examples, I will be using the most common and ideal builds for some of the faster units more recently introduced in the game.
A standard Spd boon at +10 Mia with Resolute Blade and Flashing Blade can reach 47 speed, 50 if she has Water Blessing, and 53 if she has a Speed +3 SS. A Spd boon Ayra with speed forged Slaying Edge DC Regnal Astra will reach up to 50 speed with a Water Blessing.

With a simple Hone Speed, Ally support, and Chilling Seal Debuff (thanks to being on the same team as Gunnthra for the Wind Blessing effect). Azura can reach 46 speed, and only be outsped by opposing heroes sporting 51 speed after receiving a -6 to their speed. So even though she has a pitifully low 22 def, her respectably high 48 HP and inability to be doubled by most units (unless they have a neutral speed of 57 or more at start, run Lancebreaker, or utilize Brave Weapons/guaranteed follow-up skills) will allow her to survive a good amount of physical encounters.

Needless to say, her magic bulk is pretty dank, and definitely helps her special Iceberg, play off of it. With 47 res, Azura can consistently dish out an additional 23 to 24 extra damage based on WTA/DA, if unbuffed. The main problem however, is that while Azura may have just enough speed to avoid getting doubled by key heroes, she doesn't have the speed to actually double them; which leads to my next point of cooldown count for her special.

49 atk isn't really anything to write home about, especially if she can only get one hit in. This is where the choices of SS and teammates come in. Quickened Pulse or Quick Riposte as SS in tandem with a teammate running Infantry Pulse can insure that she will be able to trigger Iceberg on the counter-attack (so long as they aren't running Guard or Firesweep weapons). With Infantry Pulse in play, her cooldown count will drop to 2.
If she runs Quickened Pulse, it will drop to 1 and she will be guaranteed the special trigger when she retaliates; however, she will not be able to double as many units or consistently trigger Iceberg thereafter. QP is more geared towards finishing off an opponent before they can get their second hit in (if they can follow-up on Azura).
If she runs Quick Riposte, she will be guaranteed the special trigger on her second follow-up on retaliation; she will be able to get Iceberg out (and double) a bit more consistently thereafter. This is only if she stays at or above her 70% HP threshold (which in this case is 34 HP), which may be difficult seeing as how she has to be initiated on to double most of the time.
With this set-up she essentially becomes a one-time nuke against mages (one who you would prefer to get rid of right off the bat before engaging other heroes); while she can tank and revenge kill even some of the stronger Green mages, such as Nino and Cecilia, I have found Bladetome buffs to be a bit troubling (unless she is sitting on a defense tile), so having an ally that can run Infantry Pulse and Panic Ploy might be a good idea. I would recommend having a Dragon ally in this case, as they have naturally large HP pools, can cover Azura's physical weakness, run DC as well (in Lightning Breath) and utilize forged weaponry for extra stats including their HP (which Infantry Pulse and Panic Ploy are dependent upon). I personally run with Fae, since my Azura is paired with my Lyn, so having a green unit around would round out the team.

Sing and WoM are no-brainer, must have, skills of choice for a singer/dancer. My C slot choice for her is to provide an additional buff to attacking/retaliating allies since I have a visible attack buff coming from elsewhere. Should Lyn fall below 50% HP, WoM kicks in and watch the duo (your sweeper of choice for your team) go to town.

Thanks for reading!