Diluc has a number of combos he can do during his uptime:
His most common combo is . This fits perfectly into the buff window of his teams.
For high upfront damage, use . This falls off significantly if the enemy is not killed within this window.
A full rotation combo can look similar to . An example video can be found here.
Regarding Weapon Choices:
These placements assume strong Flat ATK buffs such as Bennett, as Diluc is commonly played with them present in his party.
Beacon of the Reed Sea: This weapon ranking assumes one stack.
Serpent Spine: Assumes you can maintain high stacks of the weapon effect. At [R5], it is Diluc's best weapon.
Rainslasher: Only use this weapon in teams where Diluc is consistently triggering Vaporize. It scales well with refinements, potentially surpassing at [R5].
Tidal Shadow: Assumes Diluc can consistently be healed. Otherwise, this weapon ranks below .
Blackcliff Slasher: Assumes the weapon passive does not activate.
Regarding Artifact Choices:
Sets
Crimson Witch of Flames (4): Generally the best go-to set for Diluc due to how easily he can stack the Pyro DMG effect, while his Burst imbues his Normal Attack and Charged Attack with Pyro.
Marechaussee Hunter (4): Competitive with (4) when using Furina alongside Diluc.
Main Stats
Elemental Mastery: Can be preferred for the Sands if Diluc is used in a Vaporize or Melt team.
Substats
Elemental Mastery: Higher priority in Vaporize or Melt teams.
Regarding Talent Choices:
Diluc's constellations boost his Skill damage, so talent prioritization can vary from player to player.