A key recent event in White Wolf's World of Darkness metaplot. The sequence of events is as follows.
Antediluvian vampire progenitor of the Ravnos clan wakes up in India. This is generally considered to be a Bad Thing, as Antediluvians waking up is one of the legendary signs of Gehenna, which is pretty much the end of life as vampires know it.
Three kuei-jin bodhisattvas take it upon themselves to smite this Antediluvian into the ground. Cue epic fight scene that lasts for days.
The Technocracy gets wind of this. Being all hung up on order and things like that, they aren't too happy about what's going on and decide that the problem can be solved through extreme overkill. Thus, they focus a bunch of orbital solar mirrors on the Ravnos Antediluvian (for the 4x sunburn you've got to be undead to truly appriciate) and, since just sunlight can't possibly be enough, drop a few nukes on him.
By sheer coincidence, a spirit nuke goes off at the exact same time at the gateway to the Labyrinth in the Underworld. As one might imagine, this tremendous release of nasty energies in both the material and the spirit world has serious repercussions. Oh, like, touching off the Sixth Great Maelstrom, a storm of Oblivion so powerful that it utterly demolishes the metropolis of the dead, Stygia. Wraith is discontinued as a product line (*sniff*).
Well, the Ravnos Ante is as dead as dead gets, but he's not done yet! As his final act of spite, he uses his wacky vampire powers to send all his progeny into a killing frenzy, thirsting for each other's blood. The entire Ravnos clan falls on each other and eats itself to death. Said clan is now only a bloodline. Poor Ravnos.
Meanwhile, on the Mage front, all the Avatars of the Mages in the spirit world get hit by the shockwave of the spirit nuke. Many of them simply can't take the strain and shatter, creating a sort of spiritual hail across the Gauntlet between the material and the spirit world called the Avatar Storm. This is why, whenever a mage tries to cross over that barrier now, he takes aggavated damage.
Hooray for world-altering cataclysms!