Fiers

Fiers might have been a dwarven planeswalker, revered as a god by Dominaria's dwarves and [Barbarian] tribes on Otaria. He was summoned by Karona as the deity of red magic.

Fiers is part of a heavily-debated continuity issue, along with several other popular characters. While Karona spoke with Fiers during the novel Scourge, the meeting was later retconned, though no explanation has ever been provided. It is possible that Fiers is indeed a planeswalker, but if the retcon is to be believed, then the real Fiers has yet to appear in any novel.

In "The Myths of Magic"'s short story 'The Lady of The Mountain', he is a god who helped Gaea create the world while he created all the dwarves of the plane and helped create the Lady of the Mountain. However, only a few dwarves other than Otarians appear in the storyline, so it is hard to say whether or not this tale is true and all dwarves worship him, as stated in the short story.

He is also mentioned by Balthor and Jeska in their speeches indicating that they are believers of him, or expressions using his name are common in their culture.