This old man is from an old backwater elven magic school, but when he taught dark magic to his students he was banished out into the nearby forest, where he took up the hobby of artifice, in which he made various gadgets for a group of goblins that he eventually was hired by.
This eerie forest was magical in a way that made it always springtime, and this old man adapted to that environment with green robes (hence also why this is in the spring event).

Made by Whispearl