a superhero story within the superhero story, Warrior Angel;
powerful magicians, Zatara and Zatanna.
Combining these two premises, the episode called Warrior has Zatara magically rewriting and cursing a valuable copy of Warrior Angel, no 1. The rewrite is that, when betrayed, Warrior Angel becomes a super-villain. The curse is that the first reader of the copy becomes Warrior Angel and, when betrayed, becomes a super-villain. But Zatanna counteracts the curse.
A cursed superhero comic has a strong resonance with DC Comics on Earth Real.