Elemental Crown combination method is explained in this Combination Scroll.

[Required materials]
Broken Crown 150 ea.
Zelunium 20 ea.

[Elemental Crown]
A crown blessed by spirit, by wearing it you can feel the flow of nature.
DEX +3. Every 2 refine level, DEX +1.
Increases ranged physical attack by 4%.

When equipped with Burning Bow, Frozen Bow, Earth Bow or Gust Bow:
Increases ranged physical attack by 45%.

[iRO Description]
Not Available