Star Magic

Star Magic is an extremely powerful magick that works by manipulating a small stellar objects, in most cases small asteroids or comets, and drawing them into a collision course with planet, to hit the designated point. Or at least that's how half of this magic works, which requires immense ammounts of preparations to cast and is practically a strategic-level trump card.
Second part of Star Magic is simulating certain phenomena, for example by creating 'meteors' to fall from the skies from relatively low attitudes. Which is still devastating, but can destroy small village rather than whole city or continent, which is... acceptable. And is not proscribed by Imperium of Karadia and other states.
The stronger part of Star Magic is proscribed and treated as mass destruction weapons. It requires many magicians, immense ammounts of aether and lots of items. Using it is banned aside from certain, licensed individuals that are considered a trump card of the Imperium, to be used when some magical crisis will go out of control. The rest of spells is allowed, though rarely met because it requires great control and power.