Is there any official material on the effects of this day and night, particularly the night?

The Liber Mutatis Wind of Change adventure gives Geheimnisnacht effects. If there isn't something official, I'm thinking something like that + an extra helping of the sort of Morrslieb nastiness in Edge of Night with undead having benefits as the fluff indicates they are more present and earlier edition said they were "energized". There was also in earlier edition suggestion that people sometimes had prophetic dreams on this night for their fate in coming year.

i think there is a pretty nice explaination for all these special days in the year in signs of faith. there is an entire chapter devoted to folklore, festivals and holy days...hexentag/nacht should be in there somewhere too.

if you don't have signs of faith yet, i would definitely get it, all the religion is explained in great detail, even all the great temples in altdorf are described verys well!

Thanks. I have Signs of Faith, and it gives narrative outline of such days but does not give any mechanical rules to go with them.

true that, it doesnt give rules for those days

but if it says you had prophetic dreams, let them roll an intuition check before the go sleep to see, if they will have such a dream and when they wake let them roll either a simple INT or an observation check to see, how much of the dream they remember and how much they can get out of it.

with that method you can also lead them to wherever you want them to go next, works pretty fine, i do that sometimes when players get way off the plot for too long...

i'll think about that a little, maybe i can come up with stuff that might happen on hexentag/nacht...

I must have missed that, I see the bit about priests making sic checks to interpret omens but not about dreams. What page is that on? Thanks.

i actually just made that up myself on the fly, since i had a group once where i had a zealot getting strange dreams sent form sigmar and everytime she went to sleep she would have to check for the intensity of the dream with intuition, if it was a very intense dream she might wake up with 1 or 2 stress or might be relieved for the day and only suffer stress when she rolled more that one stress symbol.
when she woke she had to make her observation check to determine how much of the dream she actually remembered, ranging from 1 to 3 successes generated i think. if the dream was disturbing she would again, by remembering suffer stress or, if it was a nice dream, be more relaxed throughout the day