Guide
How the kit works
Start with Transcendence: Baleful Omen. It deals Electro damage nearby and gives nearby party members the Eye of Stormy Judgment. When a character with the Eye attacks and deals damage, it performs an AoE Electro attack. The party can trigger one coordinated attack every 0.9 seconds. The Eye also increases Burst damage based on each character's Burst Energy Cost.
Switch to teammates and use their Bursts before returning to Raiden Shogun. Those Bursts build Resolve based on their Energy Cost, up to 60 stacks. Nearby party members collecting Elemental Orbs or Particles also grant 2 stacks, once every 3 seconds. Raiden Shogun's own Burst does not build Resolve this way.
Use Secret Art: Musou Shinsetsu to consume the stacks and deal AoE Electro damage. Then attack in the Musou Isshin state: those attacks deal Electro damage that cannot be overridden and count as Elemental Burst damage. Hits restore Energy to nearby party members once per second, up to five times. The state ends if she leaves the field.
Outside that state, Origin (NA) gives her up to five spear strikes. Its Charged Attack consumes Stamina. During Musou Isshin she also has increased interruption resistance and is immune to Electro-Charged reaction damage.
Build and why
Four pieces of Emblem of Severed Fate are the first choice. Two pieces give 20% Energy Recharge, and four increase Elemental Burst damage by 25% of Energy Recharge, up to a 75% damage bonus. That suits both the initial Burst hit and her attacks during Musou Isshin.
A two-piece combination of Noblesse Oblige and Thundering Fury is another option: it gives 20% Elemental Burst damage and 15% Electro DMG Bonus. Four pieces of Noblesse Oblige are worth considering for team support; using a Burst gives the party 20% ATK for 12 seconds, but the effect cannot stack.
For main stats, use Energy Recharge or ATK Percentage on the sands, Electro DMG Bonus or ATK Percentage on the goblet, and CRIT Rate or CRIT DMG on the circlet. For substats, look for Energy Recharge first, followed by CRIT Rate, CRIT DMG and ATK Percentage. Energy Recharge also improves her Energy restoration and Electro DMG Bonus through her passive.
Engulfing Lightning is the leading weapon: it converts Energy Recharge above 100% into ATK and grants 30% Energy Recharge for 12 seconds after a Burst. Staff of Homa gives ATK based on Max HP, with a larger bonus below 50% HP. Primordial Jade Winged-Spear builds ATK on hits and gives a damage bonus at maximum stacks. The 4-star “The Catch” is an option that raises Burst damage and Burst CRIT Rate.
Leveling priority
For a Burst-focused build, I suggest leveling Secret Art: Musou Shinsetsu first. Follow it with Transcendence: Baleful Omen for the coordinated attacks and team Burst bonus. Leave Origin (NA) until last: attacks during Musou Isshin count as Elemental Burst damage, rather than ordinary Normal Attack damage.
For ascension, gather Mora, Amakumo Fruit, Vajrada Amethyst Sliver, Vajrada Amethyst Fragment, Vajrada Amethyst Chunk, Vajrada Amethyst Gemstone and Storm Beads. You also need Old Handguard, Kageuchi Handguard and Famed Handguard.
The talents also use those three Handguard materials and Mora. Their other materials are Teachings of Light, Guide to Light, Philosophies of Light, Molten Moment and Crown of Insight. You need three Crown of Insight to take all three talents to their maximum level.
Constellations worth it
Steelbreaker (C2) is the standout upgrade. The initial Burst attack and attacks in Musou Isshin ignore 60% of opponents' DEF, making it a direct increase to Raiden Shogun's own damage.
Shinkage Bygones is worth considering for three extra levels on her Burst. Ominous Inscription is useful for building Resolve faster: Electro teammates' Bursts grant 80% more Resolve, while Bursts of other elements grant 20% more.
If your focus is her own Burst damage, you can skip the later upgrades. Pledge of Propriety gives other nearby party members 30% ATK for 10 seconds when Musou Isshin expires. Shogun's Descent adds three levels to her Skill. Wishbearer (C6) reduces other nearby party members' Burst cooldowns on qualifying hits, by up to 5 seconds in one Musou Isshin state.
Teams
Choose teammates who want to use their Bursts before Raiden Shogun takes the field. They build her Resolve, receive the Eye's Burst damage bonus and can regain Energy from her attacks. You also want a teammate who can keep the party healthy.
Common mistakes
Do not switch Raiden Shogun out immediately after her Burst's first hit. Leaving the field clears Musou Isshin, so you lose the remaining attacks and chances to restore Energy. Hit opponents during the state to get those Energy triggers.
Do not expect her own Burst to build Resolve for itself. Use teammates' Bursts first, and refresh the Eye when you want its coordinated attacks and Burst bonus available.
Do not level her ordinary Normal Attack first just because you use attack inputs during her Burst. Those hits count as Elemental Burst damage. Also keep the Emblem of Severed Fate bonus cap in mind: Energy Recharge is useful, but the set's four-piece damage bonus stops at 75%.