From a page in TVtropes:
"In the year 2001, a large asteroid crash-landed in Rio de Janiero, Brazil. Out of the hollow asteroid poured an army of insect-like aliens quickly dubbed "The Bugs", killing and devouring everyone in their path. There was only one way to stop them. A mage named Bruce Von Eisenstein traveled to Brazil with a portable satellite uplink, set up the camera, and in front of the camera confronted the Alien Bug Queen...and attacked it openly using obviously supernatural magic. The resulting paradox backlash, as billions of people all over the world saw incontrovertible proof of the existence of aliens and magic, created a sudden surge of magical energy that exploded, killing Von Eisenstein and destroying the entire Bug invasion force, leaving Rio De Janiero as a smoking crater. The invasion was defeated and humanity saved, but the surge of magic also awoke from their slumber the milennia-old progenitors of vampire bloodlines, who rose up to resume their ancient blood feuds and compete for dominance. Millions of otherwise-unmagical humans were suddenly awakened with magical powers as well, and the resulting chaos threw into the open the various ancient secret struggles for control between vampires, mages, werecreatures, and their various factions and sub-factions, all fighting for dominion over humanity. The resulting War of Gehenna lasted for decades, and when it was over, an uneasy peace was struck between the warring factions."

I like the idea of using paradox as a weapon to destroy invaders, so points for creativity there, but that aside OH GOD.
Also it is my understanding that paradox isn’t always an explosion. It’s just a back lash. If the mage created sufficient paradox to eradicate the invasion paradox could manifest by simply erasing the mage from existence.
Anyway, the author took a bit of creative license. Enough STs have run paradox backlashes as detonations to make it almost plausible. *shrug*