Reminder: I tried to use as less Action Cards as possible so you can follow the steps easily. But if you have good Action Cards, you can use them if you want, as long as it doesn't disturb the instructions I gave below.
Touch Some Grass Deck
There is only 1 enemy here and all its attacks are Electro with no elemental reactions to inflict. One important thing you need to avoid is characters that can inflict elements on themselves such as Xingqiu or Kokomi. That's just giving the chance for the boss to inflict reactions on you. I use a full Dendro team because with this Electro boss, they will basically have a permanent Catalyzing Field (Next Electro & Dendro DMG +1) for the whole battle.
In my video playthrough, the most important Action Cards would be Jade Chamber because you're gonna need all the Dendro Dice you can get.
Remember that this is a boss and will be immune to Frozen, Stun, and Petrification. Not only that, but it also deals massive damage because of its passive skill that inflicts Lightning Rod on a character (increases damage by 1) + Rolling Thunder status (deal +1 damage to a character with Lightning Rod).
How it works:
Your active character will have Lightning Strike Probe on them, and once they use a Skill, they will gain Lightning Rod.
Meanwhile, the Thunder Manifestation will gain Rolling Thunder status right from the start.
In other words: Thunder Manifestation can gain +2 on most of its attacks.
A certain attack from Thunder Manifestation (Thundering Shackle from its Elemental Burst) will attack your character with the Lightning Rod instead of the active character, so beware!
First of all, start with Yaoyao as the starting character. Make sure you obtain at least 4-6 Dendro Dice (you can sacrifice some cards) and Jade Chamber Action Card. If not, restart the challenge until you get the dice I mentioned. Follow the steps below after that:
Yaoyao's Skill > Switch to Baizhu > Baizhu's Skill > End the Round
Note: Hopefully by the end of this round, you already use Jade Chamber. Other Action Card like Knight of Favonius Library or Katheryne is also good. Beware that using Katheryne may cause some difference in terms of your character's HP than mine because Thunder Manifestation attacks the new active character instead of the one in my instructions.
Baizhu's Skill > Baizhu's Burst > Switch to Collei > End the Round
Collei's Skill > Collei's Skill > End the Round before the opponent
Collei's Burst > Switch to Yaoyao (You have no other character) > Yaoyao's Skill