Illuga Build and Guide

Illuga is a 4-star Geo Polearm user who is most commonly played as a Geo Support. He specializes in buffing the Direct Lunar-Crystallize damage of Lunar DPS units, though offers some decent buffs for Geo damage as well. As a Moonsign unit, he also features important synergies with other characters in the faction.

Lunar-Crystallize is a reaction that replaces Hydro Crystallize when certain Moonsign characters such as Zibai, Linnea, or Columbina are on the team. It is triggered the same way, and doing so spawns intangible Geo Constructs called “Moondrifts” that count for enabling the effects of a team’s Geo Resonance; triggering the reaction three times causes the Moondrifts to launch a “Moondrift Harmony” which deals Lunar-Crystallize reaction damage. The aforementioned characters can also deal direct Lunar-Crystallize damage as part of their kits. All Lunar-Crystallize damage is considered Geo damage, and similar to other damaging reactions scales with EM, reaction damage bonuses, ignores DEF, and does not benefit from standard DMG%; unlike typical reactions, it can also CRIT.

Reaction Lunar-Crystallize damage takes into account the level and stats of all characters who contributed to triggering reaction based on their damage dealt to the enemy - 100% of the stats of the strongest participant, then 50% and 8% for second and third respectively. Direct Lunar-Crystallize damage is based on the multiplier and the scaling stat listed in the ability instead of level, but additionally enjoys a hidden 1.6x multiplier to its damage.

Illuga’s kit itself is simple, and centred around his Elemental Burst, which gives him “Nightingale’s Song” stacks for 20 seconds. These stacks can be consumed whenever the on-field character deals Geo damage to increase it, with direct Lunar Crystallize damage gaining an even more substantial bonus. The increase can be thought of as an extra talent multiplier scaling off of Illuga’s Elemental Mastery that he adds on when damage is dealt to the enemy, with all the other multipliers and stats used such as CRIT and Reaction DMG Bonus are taken from the unit dealing that instance of damage. By itself, the Burst grants 21 stacks; however, each Geo Construct present or generated in the Burst’s duration generates 5 additional stacks, up to 15. Since Moondrifts from Lunar-Crystallize are considered Geo Constructs, this makes generating 36 stacks a non-issue in Illuga’s best teams.

These Nightingale Song stacks are additionally strengthened by his second Ascension Passive, gaining increased Elemental Mastery scaling based on the number of Hydro and Geo characters on the team. Since Illuga himself counts, he needs 2 additional teammates of the above elements to maximize this Passive; this is almost automatically fulfilled in Lunar-Crystallize teams, where he already wants an on-field Lunar-Crystallize DPS and a Hydro teammate to trigger the reaction to begin with.

His Skill is primarily used for its fantastic energy generation, creating 4-5 particles when its projectile hits an enemy. The Tap version is quicker and almost always preferred, though the Hold Skill has better aiming and slightly further reach if needed. Furthermore, both his Skill and Burst can activate his first Ascension Passive, which grants an increased 5% CRIT Rate and 10% CRIT DMG to Geo damage dealt by all allies. If the team has Ascendant Gleam - which is always in Lunar-Crystallize teams - he additionally provides a helpful teamwide 50 Elemental Mastery buff.

His Normal Attacks, unfortunately, are useless beyond occasional use to trigger Favonius Lance or activate effects from teammates such as Xingqiu’s Burst.

Lastly, as a 4*, his constellations are far more accessible than those of limited units; luckily for Illuga, his are also quite good! His C1 reduces his Energy requirements and allows him to build more Elemental Mastery, while his C2 - while doing negligible damage - allows him to potentially trigger reactions and maintain certain artifact set bonuses thanks to providing him with off-field Geo damage. C3 is a simple but helpful Burst talent level increase. C4 and C6 are where the real value lies, however: C4 provides a DEF buff, which is useful as many of Illuga’s best teammates scale off DEF. C6, meanwhile, increases the effects of his first Passive to provide 10% CRIT Rate and 30% CRIT DMG; with Ascendant Gleam, it also increases his Elemental Mastery buff to 80. While valuable in helping put distance between him and his competition, Illuga is a complete unit at C0 and lacking his constellations does not prevent him from effectively fulfilling his role.