Ornn seems to have quite an interesting mythos surrounding him. The lore article written out for him on the League of Legends Universe site is built almost like a grouping of campfire stories or generational folktales past down from generation to generation.
In the opening, we understand Ornn has been lost to Freljordian knowledge, that he is nothing but a myth, once worshiped by a forgotten people. But we also learn more about some of the other northern deities. The Seal Sister seems to guard the seas, or watch over travelers. Volibear rolls the north and creates followers in his image. He is feared by all. But the stories to follow are essentially lost texts, bringing Ornn into the limelight after centuries of smelting in the dark.
Ornn wrestled the Freljord itself
The first story sets Ornn up as the oldest of the Feljordian deities. When he first leapt onto Runeterra, he wrestled the northern ground, bending and breaking it to his will. This is how the high plains and low valleys of the Freljord were created. Once the battle was finished, the earth opened itself up to Ornn and gifted him fire. Ornn now uses this flame and his relationship with the earth to build.
Anivia, Ornn’s sister, plays a trick and causes snow
The second story tells a tale of Ornn and his sister, Anivia. Ornn built a large home for himself in the valleys of the Freljord. It was named Horn Hall and Ornn was so proud of his creation he complimented the work, even before the time of language. As he slept in his new bed, his sister looked to get revenge on her brother for his use of lumber (which had once been her favorite tree). She tickled his nose and caused him to sneeze, setting fire to the entirety of Horn Hall. When Ornn awoke, he had no idea that Anivia was to blame, and considered his pride (by complimenting his own work) to be his downfall. So he set out to build a house that would never burn.
Ornn built his own mountain, a giant volcanic forge that he named Hearth-Home. In order to cool the mountain and make it habitable for the god of fire, Ornn dug a trench to the mountain and The Seal Sister sent cold water. The steam from the cooling process of Ornn’s mountain caused the clouds above to grow heavy. When they spilled forth, snow was born and the initial pouring lasted for 100 years.
Ornn builds the Howling Abyss
In the third story, three Freljordian sisters (Lissandra, Avarosa and Serylda) come to Ornn to ask him of a favor. The sisters had been battling creatures that inhabited their land. The first sister asked for help defeating them and Ornn said no. The second sister asked that Ornn build a pit to trap the creatures below. Ornn agreed, as he planned to build such a pit anyway.
Once the pit was built and the sisters determined that it was deep enough, Ornn returned to his forge. Finally, the sisters returned years later to ask Ornn for one final task. The third sister asked Ornn to build them a mighty bridge across the pit. In exchange for this work, she offered him metal that had fallen from the sky. Ornn accepted the task and the payment. To build the bridge, Ornn used the star metal to create a hammer to beat all hammers. He named it Hammer.
Once the bridge was constructed, the sisters polluted it with magic (a force that Ornn despises, as it ruins quality work). The incantations and spells that they laid out would seal the abyss but would slowly destroy the bridge over many years. In order to get people to stop asking him for favors, he hurled his great spade to the west. Its location is unknown. Ornn threw his fork to the east, and it is now used to rule the kingdoms under the sea. Finally, Ornn contemplated throwing his hammer into the sky, but he could not bring himself to part with it.
Ornn originated Braum’s shield
In the fourth story, Grubgrack the troll asks Ornn to build him an ornate door that will keep thieves from his treasure horde. Ornn ignores the request but Grubgrack remains persistent. Finally, the troll challenges Ornn to a drinking game. In an attempt to get Grubgrack to leave, the great ram accepts the trolls challenge. But as trolls are all want to do, Grubgrack cheats his way to victory, by placing a constantly melting shard of True Ice into Ornn’s grog.
Angry, Ornn fulfills his honor bound duty to complete the great door. Once it was finished, Ornn attached the great Ram-Door to Grubgrack’s mountain. Once Ornn was gone the troll went to count his gold and found that the door could not be opened. Enraged, Grubgrack ran to Ornn, but the smith claimed that his duty was complete. The troll was never able to open the door again.
Ornn and Volibear’s battle caused a volcano to erupt
The fifth and finally story for Ornn is a tragic one. Ornn’s brother, the evil and warmongering Volibear once came to Ornn and asked him to build his army (a mutant collection of half-men, half-bears) weapons so that he may war with others. Ornn refused. Volibear than requested that the humble people of Hearthblood, the small town of crafters that lived just outside the forge and worshiped Ornn, create his weapons of war instead.
As the request went on, Ornn became enraged at his brother, for he held the people of Hearthblood close to his heart. Knowing this, Volibear attempted to steal armor from Ornn’s forge. This caused a fight between the two brothers that lasted for over a week. When the dust settled, Hearth-Home had erupted and all the Hearthblood people had become ashes. Ornn has not been seen since, although some say that the smoking of Hearth-Home’s peak signals that he is still in there.