—Halcyon talking to Celica
Originally the High Priest of the Duma Faithful, he lost his position to Jedah after they had a dispute and escaped to Sage Hamlet in defeat. Known as the Great Sage of Duma, he lived at the edge of the village. During the game, he reveals that Mila is actually sealed within the Falchion, which is located beneath Duma Tower. Celica asks Halcyon if he can possibly help Alm. Halcyon unlocks Alm's potential, allowing him to promote to the Hero class whenever he wished from that point onward.
Halcyon is derived from the Greek name Alcyone. It is modernly used to denote a period of time in the past that was idyllically happy and peaceful, normally used in the phrase "Halcyon Days".
- Initially, Halcyon shared his portrait with Nomah. In the manga, he was given a shaven chin with a long mustache, and in Echoes: Shadows of Valentia, he was given gray hair and a small gray beard.
- While Halcyon never appears in gameplay, he is referred to as Sage in both versions of the game. In the remake, Echoes: Shadows of Valentia, Halcyon wears clothing identical to the uniform of the Sage class.
- He shares his voice English voice actor, Sean Chiplock, with Blake, Wolff, and Jerome in Echoes: Shadows of Valentia.