Hallow's End

Hallow's End is a holiday that takes place on the last night of Octabrien, the Kel'Dalar equivelant of October. It is the Kel'Dalar version of Halloween. The veil between this realm and the Abyss is at it's thinnest, so during Hallow's End spirits like the Headless Horseman tend to cross into the prime material plane to scare people and wreak havoc, until they are all banished again at sunrise the next morning.