Red magic isn't the same as Black and White magic.
Black magic takes from the world and, as far as I recall, White magic takes from the elementals. Red magic, instead, uses the caster's own aether instead of that from the world around them. The spells won't (or shouldn't) be as powerful--keeping in line with the Red Mage being a jack of all trades/master of none, but it allows them to cast the spells without having the same limitations of others.
As to how this knowledge exists, the black/white mages bailed after the war and developed the techniques to allow them to safely cast without harming their surroundings in the process.
I don't think it would be banned so much as very hard to come by since it's more or less ancient information that's only been passed down by those people. Though I imagine there exists ancient texts or whatever that could be found and such.
Black magic takes from the world and, as far as I recall, White magic takes from the elementals. Red magic, instead, uses the caster's own aether instead of that from the world around them. The spells won't (or shouldn't) be as powerful--keeping in line with the Red Mage being a jack of all trades/master of none, but it allows them to cast the spells without having the same limitations of others.
As to how this knowledge exists, the black/white mages bailed after the war and developed the techniques to allow them to safely cast without harming their surroundings in the process.
I don't think it would be banned so much as very hard to come by since it's more or less ancient information that's only been passed down by those people. Though I imagine there exists ancient texts or whatever that could be found and such.