Ludmilla
Water 
SMG 
Defender 
Burst 1 
Tetra Tier 5 Noblesse Oblige
■ Activates when the last bullet hits the target. Affects the target.
[Target] DEF ▼ 8.4% for 10 sec.
[Target] ATK ▼ 8.4% for 10 sec.
Queenly Disposition
■ Activates at the beginning of Full Burst. Affects all enemies.
Attract: Taunt continuously for 15.09 sec.
■ Activates at the beginning of Full Burst. Affects self.
Damage Taken ▼ 57.86% for 15 sec.
Snow Queen
■ Affects 10 enemies with the highest ATK.
[Target] deals 163.1% of final ATK as damage.
■ Activates when above 50% HP. Affects all allies.
DEF ▲ 12.93% for 10 sec.
Skill recommendations
Solo Raid Usage
This is based on the top 50 players of all NIKKE servers combined. Data is from enikk.app, check their website for a lot more raid data.
Extra notes
By today's standards, a really bad kit that's just underwhelming on most (if not all) PVE content. Invest only if she is your waifu.