Another one of those funny two-mode dolls. She's actually not an awful damage dealer, but her damage is still less than other dolls that are pure damage dealers. Also, despite having a rifle mode, she can't equip AP rounds so you're stuck with only the AP stats you get from her skill.

She might have use in some formations (mostly shenanigans), but most people probably won't use her.

Honestly the part you care about is the damage reduction and taunt, which can be useful depending on the type of enemy you're fighting. She wants very much to be the off-tank, in a classic ARSMG formation, and actually has decent tiles for it.

She is NOT for normal use due to her awful DPS, but the taunt can be useful vs certain enemies in the distance to keep them from interfering with the fight (for example, the new model Army tanks). The taunt can also affect random-target type enemy attacks.

She's not the worst tank, but she's expensive to raise, and she needs her ability active to really tank. Unfortunately her base ability is meh, meaning she needs all three of her special gear equipped to be actually any fucking good. With her gear, she's acceptable, with alright uptime, but her barriers are inevitably going to fail and while the evasion boost is nice, the game has other tanks that are just as good. Still, if you must use her for some reason, there are worse tanks... provided you have the gear for her, anyway.

So make sure you have her gear equipped and leveled, or don't even bother.