Quote Originally Posted by Ransu View Post
Ultima:
"We visited upon it a miracle-magic. And in its light did all life flourish.
"Yet the price for this boon would prove heavy."
"A pall descended upon this land, painting the horizon black as night"

And Joshua LITERALLY follows up that scene with "If magic caused the blight, then what of the mothercrystals" which we later find out their purpose to cast the powerful raise spell to recreate the world.

Ultima literally spells out exactly what the blight is. The use of magic caused the blight because the blight is the result of depleted aether, which again, is why all plant life dies and the soil turns black and its why you can't use magic in blighted areas as there is no aether there.
"Pride caused our downfall". Same deal.