The Book of Warlock 9. The Collector.
#9 of The Book of Warlock
Nisgarant's Sceptre is made from a mythical creature's horns, and it's bad news. Here's why.
Everything has its opposite. There is light, there is dark. There is matter, there is antimatter. There is magic... and then there is Dark magic. They repel each other, they will not mesh, will not blend, will not co-habit hosts peacefully. Both can do amazing feats that betray natural laws. Neither is inherently good, or bad. Neither is strong, or weak. They just are.
Some dimensions carry magic, and this is fine. Some dimensions carry Dark magic, and this is also fine. The trouble begins when one is carried over to the other side. It should be impossible to do. Nothing can cross through dimensions. It's a barrier untraversable by any mortal creature. You can roam worlds, roam mirror worlds even, (which are only slightly altered from the one you reside in), travel through portals leading you to the very edges of the known universe, but... other dimensions are a no go. Even in a mirror world, the laws of physics that you know and trust will be in place: there will be carbon-based life forms. The periodical table of elements will be unchanged.
In other dimensions, though, nothing is as we know it. There are new laws of science, and new elements. To bring in an alien power from an outside dimension will affect every life form it encounters. It may be physical changes, or strange dreams and visions, but it will happen. Then as it travels, disrupting life as it moves, the fabric of reality itself will begin to fray. Like an acid eating away at cloth. Eventually, the reality it resides in will purge itself. A whole universe's span of time, from its first collision of atoms to final dead wasteland of space, will cease to be. Erased. Everything in it wiped clean like a slate.
How, then, do we know about this? If crossing dimensions is impossible, surely this threat is non-existent? The answer is dragons. A law unto themselves, dragons do not have the limitations of life forms and can wander dimensions at will. This is not a problem if they roam only in magic containing dimensions, or Dark magic only dimensions. All it takes is one confused dragon making a wrong turn, however, and an entire universe is threatened. Because they like collecting things, don't they, dragons? Living specimens, rare elements, whole worlds sometimes, and somewhere out there is a dragon who likes collecting weapons. And one of the weapons in their possession was made of Dark magic, and they've just wandered into a magic dimension and had them all confiscated by the Council of Sorcerer's...