Midsummer Blossom Carolyn (Limited, Debut)
No one in particular worth rerolling for - go for anyone you'd like or just do Simple Rerolling
Simple Rerolling (Don't start with limited units): Same process as always (Link to guide)
Advanced Rerolling (Start with at least 1 limited unit): Use the Advanced Rerolling guide (Link)
As always wait 1 week before pulling any debut units.
Rafael (Boss) + Tracy + Mikael
Rafael's S1 does pretty heavy damage, but she doesn't use it often because she's preoccupied with S2 and S3.
Very easy - your usual PvE comps will work. Erica works great.
SSN is especially strong here because her Unbuffable and Unhealable will shut down Raf and Mikael, and she also has DEF Down.
Bring any of: Buff strip, def break, unbuffable, unhealable, spd down, gauge push (for ally or enemy). Not a strict requirement. Just have some of those stuff and you'll probably win.
Ith is also pretty good here as well since her Vigor and ATK down limits Rafael's damage, as well as stripping buffs, but she's also not required.
Featured 5*: Chaldea
She famously solo clears Blue Hunt. Absolutely worth picking up one if you don't have her already.
E7: Midnight Gala Lilias
AKA: just Caro since fire Carolyn is irrelevant and Clone Carolyn is called CCaro.
Caro is a DEF penetrating single target nuker with great staying power.
She has two characteristics.
First, her S3 is a single target nuke that, while having extremely poor base damage on paper, self-buffs ATK up before attacking, ignores damage distribution (like Backwards Glance) AND damage reduction (like Reluctant Compromise), and penetrates more DEF based on the HP difference between her and the target. She will penetrate 100% DEF if the target has 16,000 more HP than her.
Caro's S3 can easily oneshot someone if the conditions are right.
If any of her attacks result in the enemy having less than 50% HP, she team-buffs ATK Up and pushes her team's gauge by 20%.
Second, Caro maintains a "Pain Tolerence" buff that limits any single damage instance to 35% of her max HP (similar to Janis and Naksha but better). Her S1 also has built-in lifesteal that scales off pure ATK.
Her attacks are also guaranteed to crit (which fully ignores crit RES).
She (theoretically) has the strengths of Mirabelle and Naksha in one unit and then some more: The qualities of a single target nuker and a damage-limited lifesteal brawler.
She also has a higher deck-thinning potential than Mirabelle who traditionally requires two support units: Aoi to protect and provide DEF Down, and Saika to sustain and provide tempo and ATK Up. Caro self-buffs ATK Up, usually builds high speed, penetrates DEF, and has a built-in survival tool with Pain Tolerance.
Her S3, if the HP differential is met, can reliably delete units off the field. The attack is guaranteed to crit if hit meaning it ignores crit RES (great counter against Time Aoi, who is a high HP brawler with crit RES). She can oneshot tanks and healers as well.
Caro is also hard to cleave off the cuff due to Pain Threshold, you either need three attacks or a buff strip followed by an attack. If she is allowed to maintain PT, she'll survive like a cockroach even harder than Naksha ever could because the raw HP healed from S1 is proportionally higher than Naksha's lifesteals bring her. In other words it takes less HP healed to recover 35+% which guarantees the survival of another hit.
She's actually really hard to build. None of her gear must have HP, HP%, EHR%, or Crit rate. She doesn't build for DEF either. And if you're going for pure damage, you also want to avoid RES%. This leaves vanishingly little room for error when it comes to gear selection, and all the substats must be exacting in specification.
As a grass element Caro has a 50% chance to miss against red element units. Considering that Aoi is one of, if not the most important high HP tanks she's supposed to kill this is an insane drawback.
It is actually very difficult to achieve the full 100% penetration by creating a 16,000HP differential. A "normal" build will land Caro at roughly 6~8k HP; that places the threshold around 22~24k HP, pretty much only achieved by Ariel, Aoi, and other dedicated tankers.
DEF scalers, who normally build medium to low HP to go for high DEF, are especially difficult to achieve high penetration against.
Her damage limiter being a buff instead of a passive opens her up to all sorts of vulnerabilities:
Pain Threshold can be stripped, just like stripping Counter off of Belle
Caro will not refresh PT if she's Unbuffable
The buff can be stolen by HKD, which will obviously nosedive the match
She is also vulnerable to the usual ways to bypass damage limiters, such as simply doing a lot of attacks (much more effective here as Caro builds extremely low HP; even units who don't build damage at all, such as healers, will hit the damage threshold), damage from debuffs such as Curse or Bomb, extra damage from bonds, and fixed damage.
Riptide set is semi-mandatory as Caro MUST have as low HP as possible.
For the rest, she can run Lifesteal (for maximum staying power), Destruction (for kill security), or Speed (for tempo).
Right side CDMG + ATK% + SPD.
Aim for ATK, SPD, CDMG. No other stats needed - build RES if you have the room for it, but it is not necessary. Absolutely not worth sacrificing damage for RES.
using a lv.78 helmet (from events) is highly recommended as those have slightly less HP.
A much more advanced (and difficult) build is to use a +0 unupgraded helmet to build for as low HP as possible.
Bond choice: Any damage bond.
Caro's bond: Not that good for her, usable with Belle. 20% RES is usually not enough to do anything unless it lets you hit a threshold.
SSJ bond: Decent, not a mandatory purchase, SSJ herself is a bit down on usability at the moment but this bond does twice as much lifesteal as Aoi bond (at the cost of not having any damage bonuses)
Neko bond: Buy Buy Buy. Everyone needs a +30 copy of this.
The rest aren't worth mentioning.