Summary
InHonkai: Star Rail, characters are distinctly divided into different classes, called Paths, that define what role they’re meant to play in battle. Whatever their role may be, it’s important to know how each character is supposed to be played and, if they’re a support, what they can offer to the team.
Ruan Mei is a five-star Wind-Type character who follows the Path of The Harmony. As a Harmony character, her specialty is increasing your team’s stats in order to deal more DMG, and she does this in quite a unique way, which revolves around Weakness Break and Break Effect.

6She’s Extremely Skill Point-Efficient
When you use Ruan Mei’s Skill, String Sings Slow Swirls, she gains the Overtone effect, which allows her to increase your team’s DMG by up to 35.2 percent and Weakness Break Efficiency by 50 percent. This lasts for three turns and decreases by one at the start of her turn.
Because the duration of her Skill depends on her own turns,characters that can do multiple turns, such as Seeleor using Bronya to give your DPS another turn, won’t deplete her buff quickly. Additionally, Ruan Mei can do two Basic Attacks before needing to recast her Skill, which makes her an effective Skill Point generator and allows you more freedom to use Skill Points on your other characters.

5Build Her With Break Effect
After unlocking Ruan Mei’s third Major Trace, Candle Lights on Still Waters, for every ten percent of her Break Effect that exceeds 120 percent, her Skill additionally increases your team’s DMG by six percent, up to an additional 36 percent DMG Bonus. This allows you to grant your team a staggering 71.2 percent DMG Bonus when combined with the initial DMG Bonus granted by her Skill.
To reach her trace’s maximum DMG Bonus, you’ll need a total of 180 perfect Break Effect.

Equip her with gear that provides Break Effect, such as the Thief of Shooting Meteor and Watchmaker, Master of Dream Machinations sets, the Memories of the Past light cone, and the Talia, Kingdom of Banditry Planar Ornament set. Aiming for Break Effect substats in her Relics and Planar Ornaments is also recommended.
After unlocking her first Major Trace, Inert Respiration, she increases your entire team’s Break Effect by 20 percent.

4Use An AoE Attack After Using Her Ultimate
Ruan Mei’s Ultimate, Petals to Stream, Repose in Dream, deploys a field that lasts for two turns and increases your team’s All-Type Resistance Penetration by up to 27 percent, allowing you to deal more DMG to enemies. Additionally, attacking an enemy while the field is active will apply the Thanatoplum Rebloom debuff to them.
When enemies are about to recover from Weakness Break, Thanatoplum Rebloom will prevent them from recovering and extend their Weakness Broken state. When against multiple enemies,use an AoE attackto quickly apply Thanatoplum Rebloom on all enemies.

3Use The Right Elements To Break Weaknesses
Ruan Mei’s kit is all about Break Effect and Break DMG. Aside from extending enemies’ Weakness Break with Thanatoplum Rebloom, she can also do the following:
This allows her to deal significant DMG to enemies even as a support and without the need to break enemies’ Weaknesses herself. Use characters that match the enemies’ corresponding Weakness in order to take advantage of this special trait.

With her Skill’s Weakness Break Efficiency buff, you’ll be able to break enemies’ Weaknesses much faster.
2Use Her Technique, It’s Loaded
After using Ruan Mei’s Technique, she gains a status called Silken Serenade, which does a variety of things in both the overworld and Simulated Universe. When Ruan Mei has Silken Serenade:
Before starting a battle, whether it be a regular one or in Simulated Universe, use Ruan Mei’s Technique to quickly put yourself in a favorable situation.
1Get Her Ultimate Back Within Three Turns
Like most supports, Ruan Mei’s Ultimate provides a huge boost to your team’s performance and can quickly change the tide of battle. Aside from getting a lot of Break Effect, it’s also important to get her Ultimate back as soon as possible.
After unlocking her second Major Trace, Days Wane, Thoughts Wax, she regenerates five Energy every time she starts her turn. Equip her with gear that helps her Energy Regeneration, such as an Energy Regen Rate link rope, the Sprightly Vonwacq or Penacony, Land of Dreams Planar Ornaments, and the Memories of the Past light cone, especially at fifth superimposition, so you can reliably refresh her Ultimate after three turns.
If Memories of the Past isn’t available, you’re able to also use the three-star Meshing Cogs light cone at fifth Superimposition to get her Ultimate back in three turns.