Wizards of the Coast has revealed that Jace Beleren, a founding Planeswalker of Magic: The Gathering, will be replaced as a central hero by a new character named Tam, following storyline events in the upcoming Reality Fracture set. The reveal marks a major shift for the card game's ongoing narrative, as Jace, once a stalwart protector of the Multiverse, has instead become the storyline's villain, with his fractured psyche giving rise to a ruthless alter-ego called the Theorist.

According to the short stories accompanying the set, Jace's consciousness splintered after a failed attempt to rewrite reality using the dragon Ugin's power, spawning the Theorist, who created an alternate "Echoverse" intended to overwrite the true Multiverse. Tam, introduced earlier as a Strixhaven student, is revealed to be an authentic person built from fragments of Jace himself, originally intended as his successor; after betraying her friends to aid the Theorist, she has begun questioning his plans, setting her up as the new hero to emerge from the storyline.