In this build Raiden is used as a Hyperbloom trigger unit in a Dendro team. She is one of the best units in the game for this role. Bringing greater energy particle generation, a faster rate of seed triggering and a team ult buff in exchange for reduced team flexibility compared to another top Hyperbloom triggering unit like Kuki.

Regarding Artifact Choices:
+80 EM set (2) / +80 EM set (2): In a team with one other Electro unit it's only 1 substat roll behind Gilded Dreams (4) (3-4 substat rolls behind in a team with no other Electro units) therefore you can usually just use the set with the most Elemental Mastery substat rolls on it.

DPS
Raiden's Elemental Burst damage depends on her team's energy consumption prior to her Burst, and her Burst restores a comfortable amount of energy for her team (which is further amplified by her passive). This is especially convenient on teams that doesn't conflict with her element and wants the energy provision. (i.e. Eula, Electro, National teams, etc.).

Regarding Weapon Choices: This list assumes the average across a variety of buffs.
Staff of the Scarlet Sands: It is not recommended to build EM for this weapon as her other offensive stats still outclass it.
Skyward Spine: Assumes that you are utilizing the ATK SPD buff to access higher damage combos.
Wavebreaker's Fin: At [R5], this weapon is competitive with the strong non-Engulfing 5* options, depending on your total team burst cost.
Lithic Spear: The ranking for this weapon assumes 1 stack on its passive.
Deathmatch: With refinements, Deathmatch becomes a very competitive option with some of the strong non-Engulfing 5* options, especially in single-target situations. Even at low refinement against a single enemy it is similar to R5 The Catch in terms of performance.