I remember the boy grew up near some mountains and when a group of adventurers were passing through after completing their quest. The MC listens to them talking and awakens the system with a choice as a magician, the first ever magician class adventurer. MC goes with the party of adventurers to the capital of his country and swears loyalty to his kingdom, not the king like normally expected. Then the King gives him a mission to save the prince from internal conflict by taking a party into a dungeon and killing the party member sent from the nobles that are planning to overthrow the King that plans on killing the prince. MC swears a blood oath after the completion of the mission, which would only be possible if the King was dead, which is recognized by the gods, who give him 5 years to complete it, to restore his kingdom with the prince as the new king and he becomes the strongest magician along the way. Has elements of The Arcane Emperor like tiers of classes with tier 3 being mythical and unheard of. His dad and him turn out to be from another world and he jumped in a natural rift as a child, ending up on the world he grew up on, becoming lost to his family. His dad turns out to be a bad guy trying to suck the life out of his family to get stronger and MC teams up with Oberon, king of the fairies to kill his dad under the domain of the world tree that supports Oberon. MC dies in a prophesied fight against a world-ending Dragon and becomes a god of something near the end of the story. Think I read it two years ago or so.