Nova

Overview

Nova is a Doll who tries to do everything, and actually manages to succeed at it. She has increased Move Speed while moving, which means it's effectively always active. She buffs her own Armor if she's in the front column, meaning she has some of the highest passive Armor of SGs in general, outside Skill uptimes. She buffs the Accuracy and Crit Rate of MGs while in the back column, of which both buffs are additive meaning it both ignores Night Penalty and is much more effective than multiplicative Crit Rate. And then finally she also gives HP Shields to friendly SGs in the front column.

+80 flat Accuracy for MGs is a lot. Regular MGs have around 30 Accuracy, reduced to ~3 during Night Battles, with this they almost have triple their Daytime Accuracy.

As her checks for her buffs require her to be in a specific column to take effect, she should usually be kept in the column you are using her for for the majority of the battle, as leaving the column will immediately stop the effect from applying.

If you need her for the MG Accuracy, you would usually start her on pos5 and move her into the back column after the battle starts, so that she provides her Armor tiles to the other SG.
If you need her for the HP Shields or to help tank, you would usually start her in the front column so she can benefit from MG tiles as well.

Strengths

Excellent MG Support

She provides a flat +80 Accuracy and 30% Crit Rate buffs to MGs when in the back column. This makes MGs extremely accurate, even at Night, something that is usually something MGs fall short on.

Excellent SG Support

While in the front column, she provides other SGs with 12 HP Shield per second, active from the moment she enters the column. These HP Shields can stack up to 5 times (up to 60 HP Shield total) and have no duration.

High Movement Speed

Nova can kite quite well compared to most SGs, having SMG Move Speed.

Excellent Armor

While Nova's base Armor of 19 may seem very low, her 30% self-buff from being in the front column makes her end up having some of the highest passive Armor in actual combat, scaling better than other SGs with additional tiles as her buff is multiplicative with tiles while tiles are additive with themselves. Alone, she reaches 39 Armor with an Armor Plate and her self-buff, which is among the highest possible in the game without external buffs.

Weaknesses

Needs To Be In Front Or Rear Column For Her Effects

As such she usually needs to be used for one of her effects and that effect alone in any given fight, as she can't help tank in the rear column nor buff MGs if she's actively tanking.