Fiers

Fiers is 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.