Military action
A portal opens in the hive ward causing soilders of the blood war to spill out
A massive portal the size of a tenement opens from a Blood War battlefield to the Hive Ward in Sigil, bringing with it massive numbers of baatezu and tanar'ri in the midst of fighting. The portal remains only for a few days before receding, the two forces departing with it for the most part, but the damage caused by the spill-over remains to this day in the form of the Slags, as well as the tanar'ri creation known as the Kadyx.