Source
You can find Power's kit on the official NIKKE Twitter.
Disclaimer
A review for Power will be released once we will actually be able to see her in action and test her ourselves. The first impressions are based solely on analyzing her skills.
We also enabled her skills on her profile, so you can check them there.
Power details
Manufacturer: Abnormal
Weapon: Rocket Launcher
Element: Fire
Burst Type: 3
Class: Attacker
Rarity: SSR
Power skills

Skill 1 - Blood Fiend
■ Activates when attacking with Full Charge. Affects self.
Blood Fiend: ATK ▲ 6.4%, stacks up to 5 time(s) and lasts for 3 sec.
Power's S1 gives her a pretty massive ATK boost and all she needs is to attack enemies with Fully Charged shots. At max level and max stack, the skill will give her a whooping 32% ATK buff.
And what's best about the buff is that it isn't tied to on-kill like for example Harran, which means she can easily stack it both on boss stages and in normal stages. This combined with a pretty fast charge time (1 second) means she will only need 5 seconds to fully stack the buff.
As for the uptime of the buff it should be permanent, but it's highly likely you will need a bit of Charging Speed or use the Reload Cube on Power to actually make it permanent. Since with the 2-second reload and 1-second Full Charge time, you will be cutting it too close to the 3-second buff duration and any delay will cause the buff to fall off - especially on auto because the AI loves to hide behind cover after each shot which takes around 0.3 seconds.
Skill 2 - Blood Explosion
■ Activates when at Max Stacks of Blood Fiend after landing 18 normal attack(s). Affects self.
Explosion Radius ▲ 38.61% for 10 sec.
Reload ▲ 100%. Activates 1 time(s) per battle.
The 38% Explosion Radius bonus is a pretty huge one, but keeping it up permanently won't be possible. The 18 normal shots requirement means that Power will need to empty 3 magazines (which will take her around 22 seconds not including any buffs or Cubes) to activate the S2 skill.
And with 10-second uptime on the buff, it translates to roughly 50% uptime on the buff. Which is still pretty decent uptime, but you will need to time it right for Boss fights so she can hit multiple weak points at once.
The reload buff sadly just triggers once per battle, so it's anything big as it will just impact the early battle.
Burst Skill - Blood Hammer
Cooldown - 40 seconds
■ Affects 1 enemy unit(s) with the highest ATK.
Deals 1584% of ATK as damage.
■ Affects the same target(s) when Blood Fiend is fully stacked.
Deals 1584% of ATK as additional damage.
Well, this meme comes to mind instantly:

On paper, this looks like highest hitting single target Burst skill in the game, but we will need to compare it to Snow White's and Laplace just to be sure - since their Bursts are pretty unique.
Still, the single target nature of the skill means that using Power on non-boss stages might not be the most optimal choice, but she will definitely shine on bosses.
First impressions
Honestly, compared to Himeno who has a pretty underwhelming kit, Power actually shows a lot of promise. There's tons of synergy in her kit and also a lot of raw power, but we will need to see how it translates to actual combat - it's really hard to get a good grasp on a DPS character's potential power just by looking at their skills.
Still, for those who skipped Laplace (and we take part of the blame), Power could potentially be a good alternative to her on bosses, but we need to test her first. Stay tuned for our review which should be released within 48h of Power's joining NIKKE on the 22nd of February!