Illuga buffs Geo DMG and Lunar-Crystallize DMG after using his Burst, which grants the Nightingale's Song effect. This buff scales on Illuga's Elemental Mastery, and with his A4 talent, is further amplified depending on how many Geo and Hydro characters are in the party.

With his A1 talent, using either his Skill or Burst will grant other team members the Lightkeeper's Oath effect, which boosts the CRIT Rate and CRIT DMG of Geo DMG, and if Ascendant Gleam is active, boost the character's Elemental Mastery as well.

Lightkeeper's Oath does not apply to Illuga himself.

Nightingale's Song starts with 21 stacks, and for every Geo Construct that is on the field when his Burst is used, or if Geo Constructs are created during his Burst, Nightingale's Song gains 5 stacks, up to a maximum of 15 additional stacks.

The Moondrifts that are created by the Lunar-Crystallize reaction count as Geo Constructs.