For one, I believe Mystra (the goddess of magic) has been killed and replaced with a new version twice now to explain why the rules of magic changed between editions. If I recall correctly, cantrips (infinite use 0th-level spells) are explicitly called out as something only possible because of the effects of the Spellplague spawned by one of her deaths.
Feel like sharing some examples?
For one, I believe Mystra (the goddess of magic) has been killed and replaced with a new version twice now to explain why the rules of magic changed between editions. If I recall correctly, cantrips (infinite use 0th-level spells) are explicitly called out as something only possible because of the effects of the Spellplague spawned by one of her deaths.