Magatsu Mitake Narukami no Mikoto | Genshin Impact Wiki

This is a Rage bar which gradually fills up throughout the fight. When filled, Ei will transform into her Baleful Shadowlord form. If the player is hit by her attacks, the bar will fill up more.

Without taking many hits, this bar should fill up in about 1 minute and 30 seconds.  

Melee attacks will cause the boss to put up an Electro shield, which if attacked, can cause an AoE Electro DMG counterattack.

To counter this shield, use powerful ranged attacks, as the shield will not be activated by any ranged attack.

Sometimes, if the player is behind Ei after she does a Stun Recover or Melee attack, she will follow up with another large back attack.

After being stunned, Ei will deal a small amount of AoE Electro DMG.

Ei will slash her Halberd in a large AoE 3 times, deal Electro DMG, then summon thunderbolts around her. 

Ei twirls her Halberd as warning, then creates a huge AoE Electro DMG explosion. 

Ei summons Magatsu Electroculi which explode in a huge, almost undodgeable radius after a set amount of time. Destrotying the Magatsu Electroculi before it explodes will stun Ei for roughly 10 seconds. 

Ei will sometimes follow up her Halberd Combo with a large vertical wave of Electro damage. 

Ei can also summon 3 Magatsu Electroculi at once, in which case the best thing to do is to destroy 1 and stay away from the radius of the other 2. This will not stun Ei. 

Ei creates a small AoE Electro explosion, and calls down lightning, which will strike the player regardless of distance from Ei. A warning circle will form under the players feet to indicate where the lightning will land.

Phase 2 (Sword Form)

Executes 5 slashes of Electro DMG in a close range, with the 3rd attack dealing the most damage and the 4th attack having a huge range.

Dashes directly towards the player, performing a circular AoE attack, then lunging at the player in a straight line. 

Ei's hand will flash purple before teleporting directly to the player, and executes 2 diagonal slashes of Electro DMG.

Ei raises her sword to throw 3 Electro discs at the player, then a large horizontal wave of Electro DMG.  

Spawns 4 illusions that throw vertical slashes of Electro DMG at the player. One illusion will throw a crossed slash, indicating that it is the real Ei. Destroying this illusion will stun Ei for 10 seconds.

Phase 3 (Baleful Shadowlord Form)

Once the Ominous Destiny bar is completely full, Ei will summon pupeteer armor to increase all of her Elemental resistances and increase her damage. She also gains a very powerrful Electro Shield which also greatly increases her resistance to attacks. 

Ei will gradually lose her Ominous Destiny bar over time while in this form, which when depleted, will revert her back to her original form.

Slashes twice directly in front of her and fires an Electro projectile on the floor in front of her, which explodes after 1 second.

When the player is behind Ei, she will do a 180 slash with her sword and fire and Electro projectile on the floor, which explodes after 1 second.

Baleful Shadowlord form Ei slowly raises her sword and casts it down, dealing large AoE Electro Damage. 

Does a large AoE Electro DMG attack with a single slash of her sword in a 360 spin.

Launches 5 quick vertical waves of Electro DMG at the player, and follows up with a slow moving horizontal wave. These can be dashed through.

Summons 2 pupeteer hands to crush the player, dealing AoE Electro DMG. Can be dodged.

Blinks directly to the player and deals an uncountable amount of slashes in front of her, dealing AoE DMG.

Summons a shadow which burrows into the ground and pursues the player, dealing Electro DMG over time while the player is on top of it. After some time, the shadow emerges as a hand, and smashes down at its emergence area, dealing AoE Electro DMG. 

Summons 3 poles which each perform a shockwave of Electro DMG at equidistant times from eachother. After about 7 seconds, all 3 send shockwaves at once

Flies up into the air, leaving behind a Flower of Remembrance, which needs to be destroyed by an Electro Playable Character to deploy a shield in order to block an undodgeable attack of huge AoE Electro DMG.